However, the party was not destined to reach Gatun as speedily as was anticipated. When the boys came to the spot from which Ned and Jimmie had struck off into the jungle, or into the edge of it, rather, in pursuit of the man who had placed the bomb, Jack called Ned's attention to two skulking figures moving up the swell of the hill which the two boys had climbed the night before.

"There are some of your friends—the bomb-makers," Jack said.

"Yes," Ned replied, "they have been in advance of us for some distance."

"Watching the cottage, I presume," Jack suggested.

"More likely watching to see if we remained at home or went abroad planning mischief for them," Ned replied.

"Then they're next to us," Jimmie broke in. "I'd like to follow 'em up to the old temple an' blow 'em up."

"I have an idea that something of the sort may happen before morning," Ned said. "I had the idea that the fellows would remain away from the bomb-room for a few days, believing that we were watching it, but it seems that they are back again. We mustn't permit them to take the stuff away."

"Goin' to blow it up to-night?" demanded Jimmie, eagerly. "Gee, but that will make a blow-up for your whiskers. Say! I'd like to sell tickets of admission for this performance. That would be poor, wouldn't it?"

"It may not be necessary to blow it up," Ned observed. "If Lieutenant Gordon sent a couple of secret service men back there, as arranged, the fellows have not got into their bomb-chamber. If the secret service men did not arrive, it is likely that the plotters are moving the explosives away. We'll go and see, anyway."

"I'll run on ahead and see what's doin'," Jimmie exclaimed, darting away.

Ned caught him by the collar and drew him back, whereat the boy appeared to be very angry.

"You little dunce," Ned said, "you'll get a bullet into your anatomy if you don't be more careful. Now, you boys go on down the road toward Gatun," he added, turning to the others, "and make all the noise you want to. I'll go up to the old temple and see what is going on there. One of you would better go with me—not close up with me, but within seeing distance."

"That's me," cried Jimmie. "I'll stay near enough to see what becomes of you, and go back and tell the boys if they're needed."

This arrangement was finally decided on, and Ned and Jimmie dropped into the jungle while the others proceeded on the way to Gatun, making plenty of noise as they walked. As they disappeared the two men who had been seen just before made their appearance at a point half way up the hill.

They stood crouching in the moonlight for a moment, pointing and chattering words which reached the ears of the watchers only faintly, and then turned toward the old temple. They walked with less caution now, and it was plain to the watchers that they believed that all the boys had gone on to Gatun.

When Ned and Jimmie came within sight of the old temple half a dozen shadowy forms were seen moving about on the uneven pavements which had at one time formed the floor of a court. When the two Ned was following approached they advanced to meet them.

A conversation lasting perhaps five minutes followed the meeting, and then, leaving one man on guard, the others passed through the doorway under the vines and disappeared from view. The man who had remained outside was evidently the leader of the party, for the others had listened when he talked and had obeyed his orders, as indicated to Ned by gestures.

This man stood at the doorway behind the vines for a moment after the others had gone below and then seated himself on a crumbling wall not far away.

"Why don't you geezle him?" whispered Jimmie, who was not staying back very far, much to Ned's amusement.

"I was thinking of that," Ned replied. "I shall have to circle around so as to get in on him from behind."

"You wait a second," whispered the boy, "and I'll make him turn around so as to face the other way."

Before Ned could offer any objections or restrain the boy's hand, Jimmie launched a stone into the thicket on the other side. The watcher sprang to his feet instantly, moved away a few paces, and turned back.

"He's goin' to call the others," Jimmie whispered.

The fellow approached the doorway as Jimmie spoke, which was exactly what Ned did not want. If the man would remain outside, alone, it might be possible to capture him with little risk. If he called his companions, there would be no hope of taking him prisoner.

Ned motioned to Jimmie and the lad threw another stone into the thicket, and again the watcher moved in that direction. This time he advanced to the edge of the thicket and bent over to peer under the overhanging branches of a tree.

Before he could regain an upright position, or give a cry of warning because of the quick steps he heard behind him, Ned was grappling with him, his fingers closing about the muscular throat. It was a desperate, although a silent, struggle for a minute, and Ned might have been disappointed in the result if Jimmie had not bounced in on the two and terminated the battle by sitting down on the head of the man Ned had already thrown to the ground. As an additional precaution against any noise calculated to alarm the others, Jimmie held his gun close to the captive's nose.

"Nothin' stirrin' here," he panted. "You lie still."

"What does this mean?"

The words were English and the voice was certainly that of a man from one of the Eastern states of the North American republic.

Ned drew a noose around the prisoner's wrists and tied his rather delicate hands together firmly behind his back. Then he searched him for weapons. A revolver was found in a hip pocket, also a package of papers in a breast pocket. The fellow cursed and swore like a pirate when the papers were taken.

"This is highway robbery," he finally calmed down enough to say. "I am an official of the Zone, and you shall suffer for this."

"Gee," said Jimmie, with a chuckle, "you must have a contract to lift the canal an' the Gatun dam into the blue sky."

The prisoner snarled at the lad a moment and turned to Ned.

"Why are you doing this?" he asked.

"What are your men doing down there?" Ned asked, ignoring the question.

"They are removing explosives, explosives to be used in the work at Gatun."

"Why is it stored here?"

"For safety."

"Were your men storing this bomb," taking the clumsy exhibit from his pocket, "under my cottage for safety?" Ned demanded.

"I don't know anything about that," was the reply. "Return my papers."

Instead of returning them, Ned took the packet from his pocket and made a quick examination so far as the light would permit, of the half dozen letters it held.

The captive writhed about and cursed fluently until Jimmie touched his forehead with the muzzle of his gun and warned him against "starting anything he couldn't finish," as the boy expressed it.

"Now," Ned said to Jimmie, restoring the letters to his pocket, "you march this pirate off toward the cottage while I scare the others out of the bomb-room and blow it up."

"Blow it up before they get out," urged the boy.

"I am no executioner," Ned replied. "They doubtless deserve to be put to death, but I'm not the one to do it."

"Wait," said the captive, as Jimmie motioned him away. "If you will give me a chance to tell my side of the story those letters reveal, I may be able to establish my innocence. I can make it worth your while to listen to me," he added, significantly.

"Cripes, I smell money," laughed Jimmie.

"Go on with the boy," Ned replied. "If you want to talk with me you may do so later."

"What are you going to do with me?"

"Turn you over to the Zone government."

The captive would have argued until his friends came out and sized up the situation, and Ned knew it, so he motioned Jimmie to march the fellow away and set about the work he had in hand. He took out the bomb he had brought with him and estimated the length of time the fuse would burn. It was, as has been said, a very long fuse, and the boy was satisfied that he could escape from the danger zone after firing it.

Then, seeing that Jimmie was out of view with his prisoner, he brought out his gun and fired two shots into the air. The result showed that he had planned with judgment, for the men working below came bounding out of the doorway behind the vines and vanished in the jungle, going in a direction opposite to that taken by Jimmie.

The rapidity with which the workers in the bomb-room disappeared astonished Ned until he reflected that he might unconsciously have given a signal agreed upon between the men and the guard. At any rate, he finally concluded, the men were not there to fight in defense of the place if spied upon, but to seek cover at once, as is the habit of those caught in the commission of crime.

He had expected to drive them away by firing from the jungle, but had not anticipated a victory as easily won as this. When the workers had disappeared Ned made his way to the underground room. There he found torches burning, and a fire in the forge. The place was littered with gas-pipe cut into small lengths, and the covers had been removed from the tins of explosives.

It was clear that the bomb-makers had been at work there, and the boy wondered at their nerve. He could account for their returning to their employment there so soon after the place had been visited by hostile interests only on the ground that they believed the secret service men and the boys were being held at bay by others of the conspirators.

Wondering whether the boys who had gone on toward Gatun were safe, he lighted the fuse of the bomb and hastened up the stairs and out into the jungle. A few yards from the broken wall of the temple he met Jimmie, red of face and laboring under great excitement. He turned the boy back with a significant gesture toward the temple, and the two worked their way through the thickets for some moments without finding time or breath for explanations.

When at last they stopped for breath they found themselves about at the point where they had parted from their chums. As they came into the cleared space a flash lighted up the sky, flames went flickering, seemingly, from horizon to horizon, and lifted to the zenith. Then came the awful thunder of the explosion. The ground shook so that Jimmie went tumbling on his face. After the first mighty explosion others came in quick succession.

"That's the little ones," Jimmie cried, rolling over in the knee-deep grass to clutch at Ned's knee. "Talk about your fourth of July."

As he spoke a slab of stone weighing at least twenty pounds came through the air with a vicious whizz and struck a tree close to where the boy lay.

"If we don't get out of here we'll get our blocks knocked off," Jimmie said.

"The shower is over," Ned replied. "What were you running back for? If you had not met me, if I had gone out another way, you might have been right there when the explosion took place."

"Then I'd 'a' been sailin' around the moon by now," the boy grinned.

"Where is the captive?" demanded Ned.

"He went up in the air," replied Jimmie. "I had me eagle eyes on him one second, and the next second he was gone. He didn't shout, or shoot, or run, or do a consarned thing. He just leaked out. Where do you think he went?"

"I think," Ned replied, "that you were looking back to see the explosion and he dodged into a thicket."

"Well," admitted Jimmie, "I did look back."

Ned, rather disgusted at the carelessness of the boy, walked on in silence until the two came to the smooth slopes which led up to Gatun. There they found the boys, waiting for them, eager for the story of the explosion, and wondering at their long delay.



CHAPTER XVII.

THE WATCHER IN THE THICKET.

Between Tabernilla and Gamboa, a distance of about fifteen miles, the restless Chagres river, in its old days of freedom, crossed the canal line no less than fifteen times. At Gamboa the river finds a break in the rough hills and winds off to the northeast, past Las Cruces and off into more hills and jungles.

Where the river turns the canal enters the nine-mile cut through the Cordilleras, which form the backbone of the continent. Here at the Culebra cut, the greatest amount of excavation for the waterway is being done. This cut ends at Pedro Miguel locks, which will ease the ships down into the Pacific ocean.

Where the river turns to the northeast, at Gamboa, a wild and hilly country forms both banks. The hillsides as well as the plateaux are overgrown with dense vegetation. As in all tropical lands, the fight for survival is fierce and merciless. Trees are destroyed by great creepers, great creepers are destroyed by smaller growths, and every form of life, vegetable as well as animal, has its enemy. Every living thing springs up from the dead body of another.

Sheltered and half concealed from view in this wild country between Gamboa and Las Cruces, on the day the Boy Scouts set out in their search for Jimmie and Peter, there stood a house of stone which seemed as old as the volcanic formation upon which it stood. It was said that the structure had been there, even then looking old and dismantled, when the French began their operations on the Isthmus.

This house faced the valley of the Chagres river, having its back against a hill, which was one of the steps leading up to the top of the Cordilleras. There was a great front entrance way, and many windows, but the latter seemed closed. Few signs of life were seen about the place at five o'clock that afternoon.

From a front room in the second story the sounds of voices came, and now and then a door opened and closed and a footstep was heard on the stairway. However, those who walked about the place seemed either going or coming, for the house gained no added population because of the men who climbed the slope at the front and, ignoring the main entrance, passed on to the second floor by a secret staircase in the wall, entrance to which seemed easy for them to find.

At the hour named three acquaintances of the reader occupied the front room on the second floor of the stone house. They were Col. Van Ellis, the military man Frank Shaw had talked with in the old house near the Culebra cut, Harvey Chester, the father of the boy Jimmie and Peter had encountered in the jungle, and Gostel, the man who had approached the two boys the night before on the lip of the great excavation.

In a rear apartment, a sort of lumber-room, devoted now to wornout and broken furniture and odds and ends of house furnishing goods, was still another acquaintance—Ned Nestor. The patrol leader had met the two lost boys at Culebra, in the company of Harvey Chester and his son, Tony, and had spent enough time with the party to learn that Pedro, the ex-servant of the Shaw home, had been seen at the Chester camp, and that he had fled at the approach of Jimmie and his chum.

The story of Gostel's watching the cut at night, probably assisted by Pedro, and Harvey Chester standing guard, or seeming to do so, by day, had interested Ned greatly. The presence on the Isthmus of Pedro gave an extra kink to the problem. The attempt to capture the two boys, as previously told by Gastong, on the previous night, and the unmistakable anxiety of Chester to remain in their company, had led Ned to believe that at last he was getting to some of the people "high up" in the conspiracy against the canal. Surely a man of the education and evident wealth of Harvey Chester was not loitering along the Culebra cut just for the excitement there was in it. It was plain that he was there for a purpose, and the arrival of a man Jimmie declared to be Gostel had convinced Ned that the heads of the plot were not far away.

Gostel had greeted the boys heartily, expressing relief at the knowledge that they had escaped in safety from the jungle, and Chester had urged them all to accept of his continued hospitality. Nothing had been said of Gostel's pursuit of the two boys, and Ned had reached the conclusion that Gostel did not know that his movements had been observed.

Anxious to see what Gostel really was up to, Ned had instructed the boys to remain at a hotel at Culebra or visit the Chester camp, just as they saw fit, and had followed Gostel back to Gamboa and out to the stone house, where he had managed to hide himself in the room above described without his presence on the premises being suspected. One thing, however, Ned did not know, and that was that Jimmie McGraw, full of life and curious to know what was going on, had trained on after him and was now watching the house from a thicket on the hillside.

Ned had heard a good deal of talk since hiding himself in the rear room, much of which was of no account. Men who had delivered notes and messages had come and gone. Col. Van Ellis seemed to be doing a general business there. Some of the men who came appeared to be canal workmen, and these left what seemed to be reports of some kind.

From a break in the wall Ned could hear all that was said and see a great deal of what went on in the front room. At five o'clock a tall, dark, slender man whose black hair was turning gray in places entered the front room by way of the secret stairway in the side wall. He handed some papers to Col. Van Ellis and seated himself without being asked to do so.

"What, as a whole, are the indications?" Van Ellis asked.

"Excellent," was the short reply.

"And the latest prospect?" asked Chester.

"In the valley, near Bohio."

"What have you found there?"

"Clay-slate, hornblende, emeralds."

"In large quantities?" asked Chester, anxiously.

"There is a fortune underground there," was the reply. "Green argillaceous rock means something."

There was silence for some moments, during which Van Ellis pored over some drawings on his desk, Chester walked the floor excitedly, Gostel regarded the others with a sinister smile on his face, and Itto, the recent arrival, sat watching all the others as a cat watches a mouse.

"And this territory will be under the Lake of Gatun?" Chester asked, presently.

"Yes, very deep under the Lake of Gatun," was Itto's reply.

Again Van Ellis bent over the drawings, tracing on one with the point of a pencil.

"There are millions here," he said. "We have only to stretch forth our hands and take them."

"The wealth of a world," Itto observed.

The men talked together in Spanish for a long time, and Ned tried hard to make something of the discussion, but failed. He was convinced, however, that Chester was being urged and argued with by the others and was not consenting to what they were proposing to him.

In half an hour a man who looked fully as Oriental in size, manner and dress as Itto stepped inside the door and beckoned to that gentleman. Asking permission to retire for a few moments, Itto passed out of the door with the newcomer. Instead of going on down the secret staircase, however, the two opened a door at the end of the little hall upon which the front room gave, and appeared in the apartment where Ned was hiding.

The boy, however, was not in view from the place where they stood, and they had no reason to suspect his presence there, so he remained quiet and listened with all his ears to the low-voiced conversation carried on between the two.

"And these are the latest?" Itto asked, referring to papers in his hand.

"Yes, they are the last."

"And the showing—"

The newcomer shrugged his shoulders.

"You see for yourself," he said.

"Well," Itto said, directly, "it does not matter, does it?"

"Not in the least."

"If the information does not leak out," Itto went on, "there will be no change in our plans. We cannot afford to wait."

"For our country's sake there must be no delay."

Ned was slowly piecing this talk with the one which he had heard from the front room, and the significance of it all was sending little shivers down his back. He thought he understood at last.

As the two men left the room Ned heard a paper rustle on the floor, and at once made search for it. It was a drawing, similar to the one discovered in the bomb-room at the old temple, and was a complete sketch of the Gatun dam, the spillway, the locks—everything was shown, with character of fills and suggestions regarding the foundations. Here and there on the drawing were little red spots.

The significance of the red marks brought a date to Ned's mind. The drawings found in the bomb-room had borne a date, Saturday, April 15. If what he surmised was correct, he had only a little more than twenty-four hours in which to work. In the period of time thus given him he might, without doubt, succeed in averting the destruction of the big dam. But that was not the point.

His business there was not only to protect the Gatun dam but also to get to the core of the conspiracy and bring the plotters to punishment. The men who were plotting on the Isthmus were also plotting in New York. An inkling of the true state of affairs came to him, and he saw that in order to accomplish what he had set out to do his reach must be long enough to stretch across the Atlantic and there grapple with the subordinates in the treacherous plot.

Itto returned to the front room when the newcomer left and again the talk and the arguments went on, sometimes in Spanish, sometimes in English. Mr. Chester seemed to be asking for more time. Presently the date Ned had found on the two drawings was mentioned.

"The time set was Saturday—to-morrow," Itto said, grimly.

"That was decided upon a long time ago," Van Ellis said.

"Before the New York complications arose," Chester argued. "We did not know at that time what complications might result from the defection of one of our number. It is injudicious to go on now."

"The date referred to was also set for action in New York," Itto said.

"Yes, but the thing is inadvisable now, for Shaw has been warned."

It was plain to Ned that he would have to get away from the old stone house and decide upon some effective means of meeting this emergency. He had work to do in New York as well as in Gatun. The drawing found in the bomb-chamber had told him that. Now this new information emphasized the demand for instant action.

There was no doubt in his mind that it was the purpose of the plotters to blow up the great dam on the next day, probably after nightfall. As has been said, he could thwart the plans of the traitors by communicating with the secret service men under Lieutenant Gordon, but that course would not be apt to bring about all the desired results. He wanted to arrest every man connected with the plot. Not only that; he wanted proof to convict every one of them.

There seemed to the boy only one way in which he could attain the results sought for. He must catch the plotters "with the goods on," as the police say. He must catch them with explosives in their hands under the shadow of the dam! Ned knew that Harvey, Van Ellis, Gostel, and Itto were deep in the treacherous game, but he did not know how many others were taking part in it. He suspected that men high up in finance were back of the plot, and wanted to get the whole group.

He thought he knew why Harvey, Van Ellis and some of the others were in the plot. He was quite certain that he did. But he was not so certain of the motives of Itto, the Japanese. They might never be revealed unless the game was checked at the right moment.

There was an air of insincerity about the Japanese which Ned did not like. It seemed to the boy that he was leading the others on—or trying to lead them on—in a sinister way. The impression was in the lad's mind from the moment of his meeting Gostel that the two men, Itto and Gostel, were in the plot for some purpose of their own, a purpose which was not the accumulation of money, and which did not match the motives of the others.

About six o'clock Chester arose to his feet.

"I must go back to camp," he said.

"But there is a meeting to-night," Van Ellis urged.

"An important one," Gostel put in.

"And a midnight visit to the dam," Itto said.

"I have a previous engagement at the camp," Harvey insisted. "We have guests from New York, my son and myself."

"The secret service lads," exclaimed Gostel, scornfully. "Leave them to me to-night, and you can then keep your engagement with us."

"I have my doubts about their being connected with the secret service," Chester replied.

"We are positive," Gostel said. "They were followed from New York. We know the plotting that has been going on between Gordon and Nestor."

Much more concerning the boys was said, but Ned was too anxious to get away to pay full attention to it. Another burden was now on his mind. He must see that the boys were warned and came to no harm.

He had left them with the understanding that they might remain at the Culebra hotel or return with Tony Chester to the cottage where they had been taken when brought out of the jungle. If they had returned to the camp, they might already be in great danger.

Chester insisted on taking his departure, and the others accompanied him to the foot of the stairs in the wall, arguing with him every foot of the way. Ned stood at the door of the rear room when they returned, and while they were getting settled in the front apartment he slipped out and moved cautiously down the steps.

When he gained the grounds outside he dodged into a thicket not ten feet away from the exit and waited to make sure that no one was moving about on the outside. He was anxious to get away from the place without his presence there being known. A struggle, even if he succeeded in getting away, would put the plotters on their guard.

In a few moments he realized that the grounds were not so devoid of human life as he had believed. He heard voices on the side toward the hill, and a rustling in the thicket told him that some one was stealthily moving there.

Knowing that it would be dark in a short tune, Ned remained crouched low in the bushes, hoping to escape detection in that way, but footsteps came closer and closer to his hiding place, and he sprang up just in time to see a lithe figure hurtling toward him, the figure of a tall, slender man with an Oriental cast of countenance.

Glad that there was only one, Ned braced himself for the attack, which, however, did not come. When within a yard of its object, the lithe figure turned, staggered forward, uttered a low cry of anger and surprise, and lay swathed in a cluster of vines which had tripped and now held him to the ground.



CHAPTER XVIII.

JIMMIE RELEASES A PRISONER.

Realizing that the man who had attacked him, or attempted to, must not escape or be permitted to utter a cry of warning, Ned sprang forward and caught him by the throat. The fallen man squirmed about in the thicket for a moment and then feebly motioned for Ned to remove the pressure from his neck.

Then the patrol leader saw that the fellow had been lassoed, caught about the neck by a running noose in a slender rope. This accounted for his antics when first observed by the boy. Puzzled beyond measure, Ned loosened the noose so the captive would not die from lack of air.

The man sat up in the tangle of bushes, pressing his hands to his neck and rocking to and fro with pain. It was plain that the rope which had caught him had been drawn by a merciless hand. But whose hand was it? Ned was greatly interested in that question.

"I have released the rope so as to give you a little longer lease of life," Ned said to the prisoner, "but if you try to call out for help, or to escape, you'll be killed. Do you understand?"

Ned shifted the noose to the man's wrists, which were fastened behind his back, and relieved him of a revolver and a wicked-looking knife. Then he asked:

"Were you watching me?"

"Yes," was the short reply, in good English.

"You knew that I was in the house?"

"Yes. I saw you go in."

"Do the others know that I was in there?" asked Ned, then, anxiously.

If the others knew, then all his plans must be revised.

"No," came the reply. "I had had no opportunity of telling them."

"You were placed on guard here by the man called Gostel?"

"Yes."

"Well, who was it that pulled you down? There is something strange about that."

"I saw no one," replied the other, feeling of his throat again.

"Were others watching here with you?"

The prisoner shook his head.

"Then who did it?" demanded Ned. "That rope never dropped down from the clouds and brought you up so cleverly. Why, man, you would have had a knife into me in a second only for the rope."

"I hoped to," was the calm reply.

Then Ned heard a giggle in the thicket, and in a moment the vines parted and Jimmie looked out, a shrewd smile on his freckled face.

"Why didn't you follow the line to the end?" he asked, with a chuckle. "Then you would have come to the life saver."

"I was so rattled for a moment that I did not think of that," was the reply. "How did you come to be here?"

"I followed you," replied the boy.

"And you have been lying out there in the thicket all the time I have been in the house?"

"Why, yes, of course."

"Well, you did a good job," Ned said, taking the boy by the hand. "The cowboy stunt you have been practicing so long came into good use at last."

It was now getting quite dark, and lights showed in the house. From where the boys stood they could not see the lighted front windows, but only the reflections on the slope in front of the structure.

"I knew it would prove handy in time," grinned Jimmie. "I caught this gazabo on the fly, eh?"

"I can't understand how you managed it, in this thicket," Ned said.

"There's a clear space there where he leaped at you," Jimmie said. "I saw him rising to spring and dropped it over his head, like a bag over a blind pig. What you goin' to do with him, now you've got him?"

Ned turned to the prisoner with a smile on his face.

"What would you suggest?" he asked.

"Gee! You've got your nerve," Jimmie exclaimed. "Leave it to him an' you'll fill his pocket with yellow ones an' turn him loose to carve you up."

"If you release me," the captive replied, evidently taking the question in good faith, "I'll leave the country."

"Is that on the square?" demanded Jimmie, with a grin at Ned.

"There is a condition, however," the man added, "and that is that you make it appear that I was killed in defending the house."

"What's the answer?" asked Jimmie, while Ned stood by wondering if he had not struck a lead of good luck at last.

"I'm sick of the game," the prisoner replied. "I'm not in it for money, anyway, and the other motive is no longer of avail to me."

"If you'll tell me everything you know concerning this plot against the Gatun dam," Ned said, "I'll release you after the case is ended."

"Not a word," replied the other, closing his lips tightly, as if to shut back words seeking utterance.

"Then we'll have to find a little coop to put you in," Jimmie said. "I wish we had you back at Culebra."

While the temporary disposition of the prisoner was being discussed, and while Ned was questioning him as to the immediate movements of the plotters and receiving no satisfactory replies, the lights in the house were extinguished and the men who had occupied the front room were heard descending the stairs. In a moment some one called out:

"Gaga."

"Is that your name?" demanded Ned of the prisoner.

"Yes."

"Then answer him."

Gaga did not respond at once, and the keen point of a knife came in contact with his throat.

"Answer him."

The call came again, farther away now.

"What shall I say?" asked the captive.

"Answer him as you would have answered if nothing had happened to you here," was the reply.

The prisoner uttered a long, low cry, and the boys waited with suspended breath. Even at the peril of his life the fellow might warn the others. Ned knew how loyal the people of his nation are.

But the reply was not a warning, or a call for help. The man who had called out the prisoner's name answered now with an "All right. Remain about here." Then the men moved away in a body, taking the road to Gamboa.

"Are they coming back to-night?" asked Ned.

"I can tell you nothing," was the reply.

When the men who had left the house had disappeared from sight Ned bade the captive rise that he might be searched closely for weapons.

"Say," Jimmie cried. "There's your tall, slender man with black hair turning gray in places. Ever in New York, Mister?" he added.

The prisoner made no reply.

"You are enough like Itto to be his brother," Ned said. "Perhaps you won't mind telling me which one of you stole Frank Shaw's necklace?"

The prisoner turned his back indignantly. He was indeed a fair copy of the man called Itto, and his shoulders, narrow and high, might have made the damp stains Ned had found on the wall of the closet in the Shaw house in New York.

The stone house was now, seemingly, without an occupant and the thickets about were silent save for the noises of the night. A faint clamor came from the canal, where workmen were hewing away at the ribs of the Cordilleras, now the slight jar of an explosion, now the grinding of a steam shovel, now the nervous shrieking of the trains pushing back and forth.

The electrics over the cut drew lines of silver light on the tall trees and the foliage of the hills farther away, but here there was only a faint suggestion of illumination.

"Now you've got him," Jimmie said, presently, "what you goin' to do with him? We can't get him to Culebra or Gatun without bumpin' into some fresh guy who would want to take him away from us."

"I'm afraid you're right about that," Ned said. "We can't afford to have him get away and inform his companions that something of their plot is known."

"What would they do?"

"Make new plans, and we should have to begin all over again. As the case rests now we stand a good chance of catching every one of the conspirators."

"And the chap that stole the emerald necklace?"

"Even the necklace may drift to the surface in the eruption which is sure to take place in the near future," smiled Ned. "Now about Gaga," he continued. "Suppose you look around and see if you can't find a room in the old house which would not be used to-night, even if the plotters should come."

Jimmie hustled away and soon returned with the information that there was a room in the rear of the house, on the first floor, which would answer for a prison very well.

"But there ain't no door to it," he added, "an' the glass is all out of the window. Looks like it had been deserted for a hundred years."

"Perhaps we can rig up a door," suggested Ned.

"What's the use?" asked Jimmie. "I'm goin' to stay right here with the captive until the secret service men come an' take him away."

"But they will not come until the case is ended," urged Ned. "The knowledge that Gaga is a prisoner—arrested by a spy who overheard what was said in the house—"

"I wouldn't call myself a spy," Jimmie said, indignantly.

"There is no dishonor in serving as a spy in a good cause," Ned replied. "As I was saying, the mere knowledge of his arrest would disarrange our plans as much as his escape would. We would better make him secure here and leave him to his own thoughts, it seems to me."

"I would like to have him remain," said Gaga, much to the amazement of the boys.

"He can't resist my winnin' ways," cried Jimmie. "All right. I'll stay if you will send out about a ton of grub."

"Perhaps the boys will object to bringing it."

"Jack, or Frank, or any one of them," Jimmie exclaimed. "No trouble about that. Perhaps it will take two to bring enough."

The prisoner's bonds were loosened so that he would not feel them drawing into the flesh, but still he was left securely tied up. The room was not unpleasant, with the starlight shining in through the dismantled doorway and the broken window, and Jimmie planned to have a good rest there during his watch.

The boy had been on his feet all the previous night, wandering about the jungle, and had taken only a short rest at the Chester camp. The prisoner was so secured that it did not seem possible for him to get away, even if left there alone, so the lad rolled a dilapidated old easy chair up to the window and lay back at his ease.

For a long time neither spoke, and then the prisoner asked:

"When will I be taken to prison?"

"Search me!" Jimmie replied.

"I take it," the captive continued, "that the whole plot is discovered?"

"Bet your life!" Jimmie answered, drowsily.

"Then the United States government will have to put up a couple of extra prisons," was the comment of the prisoner.

"What you doin' it for?" demanded the boy.

The prisoner did not see fit to reply to this leading question, and Jimmie put another, equally pertinent:

"Who let you into the Shaw house that night?"

"Why do you think I was in the Shaw house?" asked the other. "Where is the Shaw house?"

"You know where it is, all right," Jimmie said. "Who was it that let you in? That is what I want to know. An' who opened the door for you to go out?"

There was no reply, and Jimmie piled on another question:

"Why did Pedro run away from Shaw's and why did he run away from Chester's camp when he saw me coming from the jungle?"

The prisoner gave a quick start, and something like a groan came from his lips.

"Is Pedrarias, the man you call Pedro, here on the Isthmus?" he asked.

"Sure he is. Didn't he report to you after he got here?"

"Living at the Chester camp, you say?"

"He was there this morning, but ran away when he recognized me. I was at the Shaw house in New York on the night of the robbery."

The prisoner checked a Spanish oath and struggled to rise to his feet, but fell back into his chair because of his bonds.

"There is bad blood between this man and myself," he said, then. "If he saw me with Chester to-day he will present himself here to-night. If he comes and finds me a prisoner, bound and at his mercy—if he comes here to-night, and finds us in this room, and you are unable to deal with him, will you cut my bonds?"

"And permit you to run away together and give me the laugh?" said Jimmie. "You're a modest kind of a fellow after all, and with nerve to spare."

"If you do this," Gaga replied, "I promise to return to you and submit to be bound again, if I come out of the conflict alive."

"Do you think Pedro would murder an unarmed man, and a bound one, at that?"

"Yes, the hatred he has for me is so great that he would take any advantage of me."

Jimmie was getting the notion that there was something tragic in the air, and was even considering the proposition seriously when there was a movement at the open doorway.

"If he comes here," Gaga went on, "you must either kill him yourself or let me. He will spare neither of us."

The boy was listening for a repetition of the sound at the doorway, when a form lifted from the crumbling threshold and stood peering in. Gaga gave a cry of terror and the intruder drew back for an instant.

The boy knew that the man whose figure he had seen outlined against the star-sprinkled sky was the man he had seen standing by the couch of the owner of the Daily Planet on the night of the robbery, the man he had seen later in the Chester camp in the jungle.

"For the love of Heaven!" the prisoner whispered.

The entreaty struck home to the heart of the boy. He had always prided himself on his love of fair play. He knew that he could not successfully defend the doorless, windowless room until the arrival of his friends, or the return of the plotters. Pedro could hide in the thicket and rain bullets upon himself and the prisoner until both were killed.

He could not make his own escape and leave the prisoner bound and at the mercy of his enemy, nor could he shoot the intruder in cold blood when he appeared in the doorway again. He was only a boy, and his inherent love of a square deal conquered.

While the movements at the door continued, he slipped over to Gaga, ran his knife through the cords which bound him, pointed to the weapons which had been taken from him, and crouched down in a corner of the room, his heart beating like a trip-hammer.



CHAPTER XIX.

A GUARDIAN NEEDING GUARDING.

Little realizing the danger in which Jimmie had been left, Ned made what speed he could to Gamboa and there looked about for some means of reaching Culebra without delay. It seemed important that he should reach the other members of his party as soon as possible and send one of the boys back to keep watch with Jimmie.

Besides, it was his intention to communicate with Lieutenant Gordon immediately. He did not expect the lieutenant to call out a squad of secret service men and place the big dam under guard. That, he reasoned, would defeat his plans for rounding up the plotters. However, it was his duty to report progress to the officer and consult with him concerning future movements.

At Gamboa he found a telephone and called the Tivoli at Ancon, but, to his disgust, Lieutenant Gordon could not be found. He tried the offices of several engineers and canal officials with no better result. At last, exhibiting a secret service badge which had been given him by the lieutenant, he mounted an engine about to leave for Culebra and was soon in that beautiful city.

The boys were at the hotel where he had left them, having declined the repeated offers of hospitality by Mr. Chester, and Tony was with them. A session was at once held in a private room, and Jack Bosworth and Harry Stevens jumped at the chance to load themselves with provisions and travel back to the stone house east of Gamboa. They were given the needed directions and sent away with a note to an officer of the railroad, who, it may be as well to state here, landed them at Gamboa in quick time and without asking any questions.

After the boys had taken their departure Frank Shaw called Ned aside.

"There's something doing here to-night," he said. "Mr. Chester came out of the parlor as red as a lobster, about six o'clock, and I guess he had a fight with a couple of Japs, Gostel and another chap I've never seen before. They parted courteously, but I could see that Tony's father was angry clear through. After he had gone back to his camp, or started for it, the Japs got a little crowd of gabbers about them and set off down the road toward Colon. They seemed mighty pleased over something, and I guess they're going to start something to-night."

"And the other man, this Col. Van Ellis. Did he come here with Chester?"

"Oh, yes; he was here, but I took good care that he did not see me. I think he went away with Chester. They were both very angry."

"Angry at the Japanese?"

"Yes; anyway, they disagreed over something. But while the two white men were angry, the Japs seemed pleased. I'll tell you what I think, Ned. The Japs are up to something the others do not like."

Ned was beginning to see a great light. Once before, since seeing Gostel, he had studied out the problem of the sincerity of the man, and had reached the conclusion that he was using Chester—perhaps others—for some sinister purpose of his own. Now he thought he saw the plot in its true light. However, he did not communicate his thoughts to the others. Had Gordon been at hand he would have confided the story to him. But Gordon was not at the Tivoli at Ancon and no one seemed to know where he was, so he was obliged to go ahead and exercise his own best judgment.

"What's doing to-night?" Glen Howard asked, when Ned and Frank returned to the room where the other boys were seated.

"We're going to Gatun," was the reply. "We're going on a special engine, and we're to leave the tracks in the outskirts and get down to the dam."

"Why, this is not the night," Frank said, surprised.

"The date on the drawings was that of to-morrow, Saturday," said Glen. "This is Friday. Of course you know what you are doing, but I wouldn't take any chances on flushing the game."

"What is it all about?" demanded Tony Chester. "There seems to be something in the air to-night. Father went away in a grouch and told me to remain with you boys, and Gastong is wandering about the city in a half-distracted manner. If you go to Gatun may I go with you?"

Ned pondered a moment before replying. There was in his mind the thought that this boy might work a miracle for his father. He saw one chance for saving Chester from the results of his connection with the plotters, and resolved to take it, risky to his plans though it was.

"No," he said, in a moment, "you are to go to your camp with a note for your father. After you deliver the note, you are to come back here and remain until you hear from me. If your father comes with you, so much the better."

"Will he tell me what is in the note—why he comes back to the city?"

"I don't think so," was the reply. "If he does come, tell him to remain close to a 'phone, here, for I may want to talk with him."

"I can't understand what all this mystery is about," Tony exclaimed.

"When did you see Gastong last?" asked Ned.

"Oh, about half an hour ago. He was in the hotel then, flying around like a hen minus her head. He asked for you, and said he'd be in the buffet when you came."

Ned lost no time in getting to the buffet, where he found Gastong, sitting in conversation with a trampish-looking fellow who seemed to be somewhat under the influence of liquor. He beckoned to Ned when he entered the room and made room for him on the leather rest at his side.

"This is Tommy, the cook," he said, when Ned was seated. "Your cook."

"You ought to join the force," laughed Ned. "I never would have known you."

"Lieutenant Gordon told me to keep watch of you boys," laughed Tommy, "but I reckon you're doing pretty well for yourselves."

"You are a secret service man?" asked Ned, satisfied now that Gordon had indeed thought it necessary to keep them all under surveillance.

"Of course," replied Tommy. "I'm not much of a cook. I guess you found that out up at the camp."

"It was thoughtful of the lieutenant," Ned said, "but, as you say, we seem to be getting on very well. Do you happen to know where Gordon is at the present moment?"

"He was to meet me here," was the reply, "but has not shown up."

"It is dollars to apples," said Gastong, "that the Japs have cornered him. He told me, on the night you went after the bomb-man, that some one was sleuthing him."

"I didn't know that you knew him," Ned said, wondering if every person he had come upon since arriving on the Isthmus was in the secret service.

"Well," said Gastong, "Lieutenant Gordon was on the squad here, you know, before he went to Mexico, and I used to meet him now and then."

"And he told you, on the first night of our arrival at camp, that we might need looking after?"

"Well, he told me that it would do no harm to let him know if I saw a mob of New York boys wandering about the works," laughed Gastong.

"So that is how you happened to be patrolling the Culebra cut in a motor car on the day the boys ran into Col. Van Ellis at the old house?"

"Well," said Gastong, "Tommy, here, kept me posted in a way, and I thought I might be useful out that direction."

"It was clever of the lieutenant," laughed Ned. "Suppose you now turn your attention to him? He may need the help of the Boy Scouts to get out of a hole himself."

"I reckon you could help him, all right," Gastong replied, confidently, but still with a look of anxiety on his face. "He has a heap of confidence in you, Mr. Nestor, but he thought best to take every precaution for your welfare. That is the reason why he surrounded you, as far as possible, with secret service people."

Ned was more than amused at the statement, for all the discoveries that had been made had resulted from the activities of the boys and himself. In fact, the only help Gordon's chain of secret service men had given his party was the thwarting of the plans of Van Ellis at the old house.

This had been important, in a sense, as the boys would otherwise have been held prisoners there and so would not have been able to come to the rescue of Ned and Jimmie at the old temple. Still, Jack Bosworth had been in that incident, and it was a question in the mind of the patrol leader if the result would have been the same without him. However, he gave the lieutenant full credit for his cautious way of going at the matter.

"The Japs, as you call them," he said to Gastong and Tommy, "have gone on toward Colon. I'm going on after them, but it may be well for you to remain here on the chance of meeting the lieutenant. He may have plans of his own for to-night."

"I am sure he has," said Tommy. "He has been active all day, with half a dozen men going and coming under his orders. He missed you this afternoon."

"I had a date to view the scenery up the Chagres river," laughed Ned.

The patrol leader went back to the room where he had left Frank, George, Glen, and Peter. Tony had left for his father's camp and George Tolford had gone with him.

"I would give considerable to know what Chester and the Japs, as they are called, quarreled about to-night," he said, but of course the boys could give him no information on the subject.

As a matter of fact, Ned thought he knew, but the thing was so incomprehensible to him that he doubted, for a time, his own reasoning. It was now nine o'clock, and it seemed to him that the time for action had come. Whether he was right in his deductions or not, he could not afford to ignore the plans he had made for the night. He did not like the idea of accepting responsibility for the important move he was determined to make, but Lieutenant Gordon was not to be found, and there was nothing for him to do but to go ahead.

"Now, boys," he said to his chums, "we are going into a game to-night that may lead to bloodshed. Again, it may prove a farce. I have only my own judgment to go on, but the matter is so serious that I'm going to take a risk. I should prefer to have Lieutenant Gordon with us, but that seems to be impossible. Get your guns ready, and I'll arrange for a railroad motor car to take us to Gatun."

"I just believe Lieutenant Gordon is in trouble," Peter said. "He was in the hotel this afternoon, just before they carried the sick man out, but has not been seen since."

Ned sprang to his feet, all excitement.

"When did they carry a sick man out?" he asked.

"Oh, it must have been about five o'clock," was the reply. "He was plumb sick, too, for they carried him out in a wheel-chair, with a sheet over his face."

"Who carried him out?"

"Why, the men from the hospital who were sent for."

"What floor?" demanded Ned, a thought he did not care to put into words coming to his mind.

"Third floor," replied Peter. "I stood out there, looking around, when the chair was brought down on the freight elevator."

Greatly to the amazement of the boys Ned darted away. In a minute he stood before the clerk's desk.

"Will you have a boy show me to Lieutenant Gordon's room?" he asked.

"Certainly," was the reply, "but you won't find him in. There have been repeated inquiries, for him this afternoon."

"Has any one been to his room?" asked Ned.

"Yes, but it is locked and the key is not here. I was up on that floor about five o'clock, when the hospital people took a man out of the room next to his, and his door was locked then."

Ned stood for a moment in deep thought, hesitating, wondering if the clerk was a man to be trusted in a great emergency.

"You look to me like a dependable man," he finally said to the clerk, "anyway, I've got to take you into my confidence. Will you take duplicate keys to the lieutenant's room and the room next to it and come with me?"

"Of course, if it is anything important," replied the clerk, "but you'll have to give some good reason before I can admit you to either room."

"Step in here," Ned said, motioning toward a little check room at the end of the counter. "You saw the sick man carried out?" he asked, as the clerk wonderingly stepped into the designated room.

"Yes, I saw him taken out. He was a stranger—took the room about noon through a friend. I did not see him at all, that is, until he was carried out, and then I did not see his face."

"You are sure it was not Lieutenant Gordon who was carried out?" asked Ned.

"Why, why, he wasn't sick. He said nothing to me of being ill."

"But he has enemies on the Isthmus," Ned went on, "and is now at work on a very delicate and dangerous job for the government. Suppose—"

The clerk waited to hear no more. He seized the keys asked for and bounded toward the elevator, taking Ned with him. When they entered the lieutenant's room they found it in great disorder. There were many signs of a desperate struggle. On the floor was a three-cornered slip of paper which had evidently, judging from the quality and thickness, been torn from a drawing roll. The scrap showed only two irregular lines, but Ned recognized them.

Lieutenant Gordon had taken into his possession the crude map of the Gatun dam which Ned had discovered in the old temple bomb-room. The next room, the one from which the alleged sick man had been taken, was also in disorder, and the door which connected the two apartments had been forced open. There was a strong odor of chloroform in both rooms.

The clerk did not need to be told what had taken place. His face turned white as chalk and his voice trembled as he asked:

"What is to be done? Think of the lieutenant being carried off from this hotel in the daytime. It will ruin us."

"First," Ned replied, "you must make up your mind to keep what has been done a profound secret. You may tell the proprietor if you see fit to do so, but no one else must know."

"But the secret service men must be told."

"Not now," Ned replied. "I have an idea that I can restore the lieutenant to his friends without any row being made over the matter."

"But how? I don't understand."

"At least," Ned urged, "wait until two o'clock to-morrow morning. I am going out now on an expedition which may reveal many things, if I succeed. If I fail, why, then you must notify the secret service men and look for me in some of the pools about Gatun."

The clerk finally consented to this arrangement, and in ten minutes Ned and his chums were speeding toward Gatun on a railroad motor car.



CHAPTER XX.

THE SPOIL OF THE LOCKS.

At eleven o'clock that night the workmen employed at the locks, the spillway, and the barrier of the Gatun dam found that their lights were not working satisfactorily and sent word back to the electric department that something was amiss.

The electric department sent word back to the men in the excavations that the lights were all right so far as they were concerned, that they were doing their full duty efficiently, and that the men with the shovels, the dynamite and the dump cars might go chase themselves.

This expression of fact and permission did not make it any lighter at the workings, but the men kept on, in the intermittent showers of illumination, and grumbled while they excavated and piled in the concrete. At last, just before midnight, the incandescence did not come back to the globes, and the men gathered in groups to discuss the matter and express heated opinions of the efficiency of the men in charge of the lighting plant.

The workmen moved about here and there in the shadows and clambered like ants over the great bulk of the dam. No one looked to see that the men assembled in the workings all belonged there. At midnight four men who did not belong there entered the excavation which leads from the bottom of the lower lock to the sea-level channel into Limon Bay, which is a child of the Caribbean Sea.

These four men moved about as if accustomed to the situation, only now and then they halted and whispered together. Other men, workmen, were doing that, however, and so these four passed on up to the foot of the spillway without attracting attention.

Here they separated, one to the west, one to the east, where the locks are, and one to a position half way between the spillway and the west side of the locks. The fourth man remained near the foot of the spillway.

Due primarily to its size, Gatun dam has received, perhaps, more attention in the United States than is its due. There is nothing especially difficult or complicated about this dam, and many dams have been successfully built in this country to withstand much larger pressures and greater heads of water than the Gatun dam without being given one-quarter of the attention.

Gatun dam fills the opening between the hills at Gatun through which the Chagres river flows to the Caribbean Sea. It consists, if it may be regarded in the light of a finished production, of a water-tight center or core composed of sand and clay mixed in proper proportion and deposited hydraulically; that is by being pumped in.

On each side a wall of rock confines this core. The bulk of the dam rests on impermeable material of sufficient supporting power. The locks and spillway are considered a part of the dam.

The locks are built in an excavation at the east end of the dam, in rock, and will lift vessels from the Atlantic level to the level of the Lake of Gatun. The spillway is a concrete-lined opening cut through a hill of rock near the center of the dam. When supplied with suitable gates, it will regulate the level of the lake.

The dam proper is about 9,000 feet long over all, measured on its crest, including locks and spill way, but for only five hundred feet of this great distance will it be subjected to great pressure. During this space there is, or will be, a weight of about eighty-five feet depth against the barrier. For only about half its length will the head of water on the dam be over fifty feet.

It will be seen from the above description that the point of attack on the dam would naturally be where the pressure is greatest, also at the locks, which would make a mighty channel for the flood of water, and which would be difficult to repair. The spillway, too, if enlarged by explosives, would make a nasty hole to build up.

Now another point which Ned had considered when he looked over the crude drawings he had discovered. Hard rock underlies the dam near the surface of the ground except for about one-fifth of its entire length. Here the rock dips down to a minimum depth below sea-level of from 195 feet in the depression east of the spillway to 255 feet in that west of the spillway. Here, of course, would be another point of attack by one designing permanent mischief.

These depressions or valleys have been slowly filled during past ages. Measured from sea-level down, the first 80 feet consists of sand and clay; the next 100 feet or so is stiff blue clay, while the last 20 to 60 feet is a conglomerate, composed of sand, shells and stone. It will be readily seen that great damage might be done by a raging torrent boring into the sand and clay of the first strata.

Now, the outer walls of rock are 1,200 feet apart, the interval being filled with spoil from the canal and lock excavations. The south "toe," as it is called, has a height of 60 feet, while the north or down-stream "toe" is 30 feet high. Spoil from the excavations will be dumped outside the "toes" until the dam is 2,000 feet in width at the bottom. The top of the dam is, or will be, 30 feet above water level and have a width of 100 feet. The channel of the spillway is 300 feet wide.

Ned had figured it out that one attacking the dam would naturally seek to enlarge the locks and the spillway and also to burrow in under the bulk of the dam where the sand and clay had been washed in below sea-level by countless years of flood and storm. The locks and spillway, enlarged, would require years of active work for repair; the sand and clay, if subjected to high explosives, would cause the crest of the dam to drop in on the north side and so enfeeble the entire structure, requiring the gigantic work of constructing new foundations.

Therefore, when Ned saw the four men moving toward the spillway, saw them part and seek the vulnerable points which have been described above, he knew that the time he had been waiting for had come. The treacherous rascals were there to do their wicked work that night—to carry out plans long formed and well considered—and they were opposed only by the inexperienced patrol leader from New York and his three chums, Frank Shaw, Glen Howard, and Peter Fenton. It will be remembered that Jimmie McGraw, Jack Bosworth, and Harry Stevens were at the old stone house on the road to Las Cruces from Gamboa, and that George Tolford had accompanied Tony to the Chester camp.

On reaching Gatun the boys had slipped out of the lights of the station and descended immediately to the bottom of the cut. They were at once accosted by a foreman, but the explanation Ned gave seemed more than sufficient, for Dan Welch, the man in charge of a group of workers on the locks, at once summoned his assistant to the job and remained with the boys.

"I have heard about you, Ned Nestor," Welch said; "in fact, about half the men in the workings at Gatun have heard of you."

"I don't understand how," replied the puzzled boy.

"Well, through that bomb business at the cottage. You see, it leaked out. When the attempt to blow up the place was reported, the men naturally asked what the dickens the scamps wanted to blow up a crowd of sightseers for, and then it came out that you came here with Lieutenant Gordon, and that's about all."

It was at this time that the lights suspended operation. Welch glanced about the busy scene for an instant and sat down on a box which contained tools.

"No use," he said. "The electric men work as they please. We'll wait here and lose our record. Did you say where Lieutenant Gordon is to-night?"

"I did not, because I wasn't asked," was the reply, "and because I don't know where he is."

"He's a good fellow, Gordon," Welch exclaimed. "I'd go far and fast to do him a favor. I hope he's coming out of this game all right."

Then Ned sat down on the tool-box and told Welch the story of the abduction of the lieutenant, and also the story of what was going on there that night, as he understood it. To say that Welch was profoundly excited does not half express the foreman's state of mind as he listened.

"My God!" he cried, when Ned paused. "To think of the wickedness of the thing. To destroy the work of years. To delay the completion of the canal for a decade. What can we do? In this darkness, the spoilers can work their will."

"I think I know who they are," Ned said. "We must find them."

"It is too bad that the lights should fail us just at this time," the foreman said.

"I have an idea that the plotters arranged for that," Ned said, then.

"But how?" demanded Welch. "The plants are well guarded. You know, of course, that we are all on the lookout for something of the kind? We thought we had provided against any sudden surprise. Where are we to look for them?"

Then Ned pointed out the probable points of attack, and Welch sprang to his feet in a fuming passion.

"The spillway and the locks," he cried. "And the point where the soft earth extends under the dam! Come!"

"Bring four of your men who can be trusted," Ned advised, not leaving the box.

"Yes, and what then?"

"Send a man to the light station and have tracers sent out, but instruct him not to have the lights turned on until you give the signal."

"I understand," the foreman said. "We'll catch them with the goods!"

Four men, workmen, were strolling along the danger points within five minutes, and another moved toward the electric switches which governed that part of the illumination. Ned and Welch remained near the spillway. The three boys, after whispered instructions from Ned, moved along the line passing word from man to man.

It was a long and heart-breaking half hour, seemingly double that time, that followed. The man from the switches came back and whispered to Welch, and at that moment a shrill bird-call sounded in the darkness. This, in turn, was followed by the report of a revolver, and then the light leaped into the globes, making the place, the entire length of the canal dam, the spillway and the locks, as bright as day.

There came a half-hearted explosion from the direction of the locks, followed by more shots. Then everything was in confusion, and groups of men gathered in four spots along the line. There were more shots and then the three boys rushed, panting, to the position Ned and the foreman had taken.

"They've got them!" Frank cried. "They've got every man of them—four Japs with lighted fuses in their hands!"

"There must be more than four!" Welch cried.

"I think not," Ned replied. "This is hardly a job for many men to work on! The four dare not take others into their confidence. Come! Suppose we gather them in?"

"How do you boys know they've got them all?" demanded Welch. "The four men must be some distance apart."

"Not too far for a revolver to carry a signal!" smiled Ned. "You probably noticed four groups of shots? Well, the boys who have been acting as messengers from man to man gave directions as to the number of shots for each group!"

"I see!" said Welch. "You don't need any whiskers, boy, to do the brain work of a man. Here comes the first batch!"

Itto and Gostel were the first ones brought in. Itto was wounded fatally and Gostel was bleeding from a wound in the side. The other men were not injured. They stood in a little group for a moment, and then Itto dropped to the ground.

The reports of the men who had been sent out to the danger points showed that each one of the four had been caught lighting a fuse, the bombs having been set.

"We were forced to work before we were ready," Gostel said, defiantly. "Our government discovered what was going on, and we would have been arrested to-morrow. So we were obliged to take the risk to-night. We were working for the glory of the Emperor, but he forbade it!"

"I did not believe the government of Japan would descend to any such despicable work," Ned said. "You fellows are cranks! You would have worked great harm to your Emperor if you had succeeded. By the way," he added, "what did you do with Lieutenant Gordon?"

Gostel glared at his questioner, but Itto beckoned Ned to his side.

"The old stone house on the road to Las Cruces!" he whispered.

"Where is that?" asked Welch, who had bent over the wounded man and heard the words.

"I know," replied Ned. "One act of this tragedy has already been pulled off there. Have your men take these cranks to Gatun and get a railroad motor. We must get to Gamboa without loss of time. It is only a short distance from there to the place he speaks of. If they took Lieutenant Gordon there a prisoner, they are likely to have had a warm reception, for three of my chums are there!"

But it was not necessary for them to go to the old stone house. At Gamboa they found Lieutenant Gordon and the three boys. Jimmie excitedly related the sensational occurrences at the house.

"Jack and Harry came up," he concluded, "just as the two men, Pedro and Gaga, were going together with knives. I was scared into a trance! The boys covered them with guns an' we trussed 'em both. You never saw people more surprised in your life. Then two men brought in Lieutenant Gordon, all nicely tied up, and went away, or started to go away. Well, they wasn't prepared for an attack from the bushes, and we have four prisoners in a cell of a jail at Gamboa, right over there!"

In an hour the boys were all back at Culebra, with Lieutenant Gordon looking angry enough to eat sinkers, as Jimmie said. The officer though pleased at the general results, did not like to admit that he had been captured by the enemy and rescued by the Boy Scouts, the little fellows he was guarding!



CHAPTER XXI.

THE TANGLE STRAIGHTENED OUT.

It was nearly daylight when the tired party entered the lobby of the hotel at Culebra. The eight men who had been captured were all under strong guard, the bombs had been taken from the dam, and the danger was over.

"Now," Lieutenant Gordon said, "we'll go after the men higher up."

He started back as he uttered the words, for Mr. Shaw, Harvey Chester, Col. Van Ellis, George Tolford, and Tony Chester came hastening toward him.

"There are three of the men higher up!" the lieutenant shouted. "I arrest you, gentlemen, for treason!"

The three men drew back in surprise and Mr. Shaw stepped forward.

"What does it mean?" he asked. "I sailed from New York the day after the boys left, but reached Culebra only to-night. When I came here I found Mr. Chester and Mr. Van Ellis waiting for news from Ned Nestor. What does it mean?"

"It means!" shouted Gordon, "that your dupes are all under arrest, through the efforts of Nestor, and that the Gatun dam is no longer in danger. It also means that you three men are under arrest! I suspected, that night in your house in New York, Shaw, that you were trying to lead me to a false trail."

Mr. Shaw glanced indifferently at the officer and motioned to a distinguished looking gentleman who had been observing the scene from a distance.

"This," he said, "is Colonel Hill, your chief, Gordon. He came on from New York with me. Let him speak."

"But the others are prisoners," insisted Gordon.

"I have an idea," Mr. Shaw said, "that Nestor knows more about the complications of this case than any one else. Suppose we let him sum it up?"

"I am sure he can do it!" growled Gordon.

Although it was now broad daylight, and all were tired and in need of sleep, the party went to a private parlor and Ned began the story of the case, first having a short talk with Jimmie, who had listened to a confession from Gaga.

"The plot against the Gatun dam," he said, "did not originate with the business men who were looking for emeralds along the line of the cut. When I first sized up the case it seemed to me that the men interested in emeralds, including Mr. Shaw, were willing to delay the completion of the canal in order that they might have time to develop mines believed to be fabulously rich in emeralds."

"That is the way it looked to me," the lieutenant said.

"I began work along that line," continued Ned, "for the news that Mr. Shaw was interested in emerald mines, and his refusal to reveal the contents of the papers he had secured, led me to the opinion that he had been approached by his partners with a proposition to destroy the Gatun dam, that he had their proposals in writing, and that he had refused to become a party to such an outrage."

"Then why didn't he tell us who the men were?" demanded Gordon.

"Because," was the reply, "he did not think his partners, Mr. Harvey Chester and Col. Van Ellis, would go to the extremity proposed. He thought they would change their minds when the enormity of the crime was set before them. In fact, he suspected from the first that they were being urged on by others having private ends to gain by the destruction of the dam. Besides, he thought himself capable of handling the situation alone. Is that true, Mr. Shaw?"

"All true," was the reply, "but I don't see how you found out what was in my mind," he added, with a laugh.

"It was all very clear to me, in time," was the reply. "Unless I am very much mistaken, you, Mr. Shaw, fearful that the enemies of the canal scheme might act too quickly, gave the information to the government which led to Lieutenant Gordon being put on the case. Is that right?"

"Yes," was the reply, "that is right, but how—"

"All in good time," Ned went on. "Now, the fact that you had warned the officers of the government became known to your associates in the emerald business. That is, it became known to the men who were drawing the associates into this crime. It was then necessary for them to get the papers they had given to you, the maps and plans of the best points of attack. The papers mentioned names, and would have convicted every one of them of treason."

"Where did you get a glimpse of the papers?" asked Mr. Shaw.

"I have never seen them," was the reply, "but what took place shows what they contained. When you left the Isthmus, Pedro, real name Pedrarias, was induced by some of the conspirators to go with you as your servant. His real duty in your house was to steal the papers before you turned them over to the government."

"I had no intention of doing that," the editor said.

"But the conspirators did not know that," Ned went on. "Now, while Pedro went into your employ for the purpose of stealing the papers he also went for a purpose of his own. It was his longing to possess the emerald necklace—which had long been in his family—that induced him to become a servant, though the large sum of money the conspirators paid him was a consideration, he being very poor.

"You all know what happened. Pedro did not succeed in getting either the papers or the necklace. He remained in the house until the others became anxious and sent three men on to New York to accomplish what Pedro did not seem capable of doing. One of these men was Gaga and one was Itto.

"Working under instructions from his confederates, Pedro let Gaga into the house about six o'clock one rainy night. He remained inside so long without reporting to those outside that they demanded admittance, and Pedro was obliged to let them in. This must have been about nine o'clock. When Itto and the other man entered, they went at their work roughly. They assaulted Mr. Shaw and searched his rooms which had already been searched by Gaga. Then they went upstairs to search Frank's room, and Pedro tried to turn them back.

"He did not trust them, being afraid they would secure the necklace. By the way, the chances are that he did not know that Gaga was still in the house. Well, when Pedro opposed their passage and Frank ran out, the two fled, finding the night-bolt off at the street door. Then Gaga got the necklace and got out of the house during the excitement.

"It may be well to say here that Pedro did not leave the house to further conspire with the canal plotters. When he found that Gaga had indeed stolen the necklace he went after him. He did not care where the others went, or whether they secured the papers or not. It was the second man, the one with Itto, who followed us on board the boat and was named His Nobbs by the boys.

"Pedro went back to Mr. Chester, who had been prominent in locating him in the Shaw house, and waited for a chance at Gaga. By this time both Mr. Chester and Col. Van Ellis had decided to turn the plotters over to the government and take their chances on arrest, for of course the arrested men would accuse them of being at the head of the conspiracy."

"Col. Van Ellis was going to lock us up and see how long we could go without food!" Frank exclaimed. "That doesn't look much like the work of a contrite heart!"

"You would not have been starved," Van Ellis replied, with a smile. "At that time our friends, the Japs, were watching our every movement, and Mr. Chester and myself agreed to let them play their game a little longer in order that they might be caught and punished."

"What about the mysterious Jap men you are talking about?" demanded Jack Bosworth. "I am anxious to know how they tangled these three business men up in the game."

"Is it true," Ned asked of Mr. Shaw, "that Gostel and Itto first proposed delaying the work on the canal?"

"Yes; they first suggested it."

"They told you of emerald mines under there?"

"Certainly."

"But they never took you to see the mines?"

"No; we took their word for it."

"Well, they lied to you. There are no emerald deposits under the line of the canal. Their purpose was to get you involved in a scheme to blow up the dam, believing that you, by your influence, would be able to ward off suspicion after the job had been accomplished."

"But why?"

"Because they are cranks. They believed they would be doing their Emperor a great favor by destroying the canal. They were insane on the subject. They believed that Japan could never become mistress of the Pacific with the canal in operation and the fleets of the world passing through it.

"Well, they carried on the plotting, made their bombs, and fought us boys, as you all know. Their plans were progressing satisfactorily, for they did not know that Mr. Shaw, Mr. Chester, and Col. Van Ellis would have stopped them at the risk of their own lives, had they been able to do so, until the Japanese government got wind of what was on.

"Then these cranks were warned by the Japanese officials to stop. Instead of doing so they abducted Lieutenant Gordon and advanced the date of the crime one night. The abduction was cleverly planned and executed, but Mr. Chester learned of it, and there was a row about it. But there was no suspicion on the part of Mr. Chester that the job was set for last night, I take it. Is that true?" he asked, turning to Mr. Chester.

"Yes, I was completely deceived, and only that you boys were on guard the dam would have been blown up!"

"I overheard their plans in the stone house," Ned continued. "Mr. Chester and Col. Van Ellis went there to call the whole thing off, but Gostel and Itto lied to them. I heard Gaga admit to Itto that there were no emeralds under the canal line. I found there another map of the dam, with marks where the bombs were to be placed. Then, when I got back to Culebra and found that Lieutenant Gordon had been abducted, I knew that the job was set for that night."

"I was sorry you went without me," Mr. Chester said.

"I wanted you here when the end came," Ned replied, "and so sent for you. I wanted you where you could not be accused of complicity in the crime, for I knew that you were innocent. Your only fault was in listening to the men at all."

"Yes, we should have listened to Mr. Shaw instead of the Japs," Mr. Chester admitted, "but it has come out all right. The peril is over. Now, what about the necklace?"

"Gaga carried it with him, lugged it about on his person," Ned said, "and Jimmie secured it after his arrest at the stone house. Pedro would not have been captured if he had not followed Gaga there with the intention of murdering him and securing the necklace. Yes, the bauble is in Frank's possession again!"

"And that closes the case," laughed Mr. Shaw, "and you boys may as well go back to New York with me. The reward for your work, Mr. Nestor, will be large, and you may as well take a rest. We will leave the prisoners in the hands of the law."

"Wait a moment!" said Col. Hill. "We are in need of a herd of Boy Scouts, just like this one, up in the Philippines. Will you go, boys?"

THE END

* * * * *

The lads were anxious to go, of course, and the story of their adventures there will be told in the next book of the series, entitled:

"Boy Scouts in the Philippines; or, the Key to the Treaty Box."

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Motor Boat Boys Series By Louis Arundel

1. The Motor Club's Cruise Down the Mississippi; or The Dash for Dixie. 2. The Motor Club on the St. Lawrence River; or Adventures Among the Thousand Islands. 3. The Motor Club on the Great Lakes; or Exploring the Mystic Isle of Mackinac. 4. Motor Boat Boys Among the Florida Keys; or The Struggle for the Leadership. 5. Motor Boat Boys Down the Coast; or Through Storm and Stress. 6. Motor Boat Boy's River Chase; or Six Chums Afloat or Ashore. 7. Motor Boat Boys Down the Danube; or Four Chums Abroad.

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Motor Maid Series By Katherine Stokes

1. Motor Maids' School Days 2. Motor Maids by Palm and Pine 3. Motor Maids Across the Continent 4. Motor Maids by Rose, Shamrock and Thistle 5. Motor Maids in Fair Japan 6. Motor Maids at Sunrise Camp

For sale by all booksellers or sent postpaid on receipt of 75c.

M. A. DONOHUE & COMPANY 701-733 S. DEARBORN STREET :: CHICAGO

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Radio Boys Series

1. Radio Boys in the Secret Service; or, Cast Away on an Iceberg FRANK HONEYWELL 2. Radio Boys on the Thousand Islands; or, The Yankee Canadian Wireless Trail FRANK HONEYWELL 3. Radio Boys in the Flying Service; or, Held for Ransom by Mexican Bandits J. W. DUFFIELD 4. Radio Boys Under the Sea; or, The Hunt for the Sunken Treasure J. W. DUFFIELD 5. Radio Boys Cronies; or, Bill Brown's Radio WAYNE WHIPPLE 6. Radio Boys Loyalty; or, Bill Brown Listens In WAYNE WHIPPLE

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Peggy Parson's Series By Annabel Sharp

A popular and charming series of Girl's books dealing in an interesting and fascinating manner with the life and adventures of Girlhood so dear to all Girls from eight to fourteen years of age. Printed from large clear type on superior quality paper, multicolor jacket. Bound in cloth.

For sale by all booksellers or sent postpaid on receipt of 75c.

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The Aeroplane Series By John Luther Langworthy

1. The Aeroplane Boys; or, The Young Pilots First Air Voyage 2. The Aeroplane Boys on the Wing; or, Aeroplane Chums in the Tropics 3. The Aeroplane Boys Among the Clouds; or, Young Aviators in a Wreck 4. The Aeroplane Boys' Flights; or, A Hydroplane Round-up 5. The Aeroplane Boys on a Cattle Ranch

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The Girl Aviator Series By Margaret Burnham

Just the type of books that delight and fascinate the wide awake Girls of the present day who are between the ages of eight and fourteen years. The great author of these books regards them as the best products of her pen. Printed from large clear type on a superior quality of paper; attractive multicolor jacket wrapper around each book. Bound in cloth.

1. The Girl Aviators and the Phantom Airship 2. The Girl Aviators on Golden Wings 3. The Girl Aviators' Sky Cruise 4. The Girl Aviators' Motor Butterfly

For sale by all booksellers or sent postpaid on receipt of 75c.

M. A. DONOHUE & COMPANY 701-733 S. DEARBORN STREET :: CHICAGO

THE END