Charlie Anderson, who had taken the earliest watch, roused Blake at the appointed time, and reported:

"All quiet so far."

"Then you haven't seen anything of our friends across the hall?"

"Not a thing. Just as we arranged, I've had my eye at the hole, but their doors have both been closed. Maybe you'll have better luck."

"I don't think it will be good luck at all to see one of them sneak out to flash a signal to a waiting submarine, or one that may be following us all the while, waiting for a chance to strike. But I will call it exceedingly good luck if we can stop it," said Blake.

"Go to it, old top!" exclaimed Macaroni, dropping into what he thought the latest English slang. "I'm going to turn in."The lanky helper of the moving picture boys had spent the hours of his watch with his eye close to a small hole that had been bored in the door of the boys' stateroom. The hole gave a view of the staterooms of Lieutenant Secor and Mr. Labenstein, which adjoined. And, as Charles had said, he had not observed either man leave his apartment.

If what the boys had only guessed at were true—that one or both of the men contemplated giving a signal to the enemy by means of the flashlight—the time for it had not yet come.

"Well, I'll try my hand," Blake said. "You turn in, Mac, and if I need any help I'll call you. If I don't see anything up to about one o'clock I'll let Joe do his trick. Good-night and pleasant dreams."

Charlie did not answer. He was already in his bunk and asleep, for he was tired, and the last half hour of his watch he had kept himself awake with difficulty.

Then Blake began his turn of duty. He took a position at the door where he could look out through the hole into the dimly lighted corridor. He had a view of the doors of the staterooms of the two men who were under suspicion, and as soon as either or both of them came out he intended to follow and see what was done.

For an hour nothing happened, and Blake was beginning to feel a bit sleepy, in spite of the fact that he had rested during the early part of the evening, when he was startled by a slight sound. It was like the creaking of a rusty hinge, and at first he thought it but one of the many sounds always more or less audible on a moving ship.

Then, as he tuned his ears more acutely, he knew that it was the squeaking of a hinge he had heard, and he felt sure it meant the opening of a door near by.

Through the hole he looked at the door behind which was Levi Labenstein, whether sleeping or preparing for some act which would put the ship in peril and endanger the lives of all the passengers, could only be guessed.

Then, as Blake watched, he saw the door open and the German come out. Labenstein looked around with furtive glances, and they rested for some little time on the door behind which Blake was watching. Then, as if satisfied that all was quiet, the man stole silently along, the corridor.

"Something doing," thought Blake. "Something doing, all right. He has something in his hand—probably my flashlight. Much good may it do him!"

As Labenstein passed the stateroom where Lieutenant Secor was quartered, that door opened softly, but not until the German was beyond it. And then Blake saw the Frenchman peer out as though to make sure his fellow-conspirator was fairly on his way. After that the lieutenant himself emerged and softly followed the German.

"Both of 'em at it," mused Blake. "I'd better rouse Joe and let him keep track of one, in case they should separate."

A touch on Joe Duncan's shoulder served to arouse him, though he was in a deep sleep. He sat up, demanding:

"What is it? Are we torpedoed?"

"No, but we may be," was Blake's low answer. "Keep quiet and follow me. Secor and Labenstein have both gone up on deck, I think. We'd better follow."

"Shall we tell Charlie?" asked Joe, as he slid from his berth. Neither he nor his chums had taken off their clothes.

"Yes, I guess we'd better get him up," Blake answered. "If you and I have to watch these two fellows, we may need some one to send for help in case anything happens. Come on, Macaroni," he added, leaning over their helper and whispering in his ear. "Wake up!"

Charles was up in an instant, a bit confused at first, as one often is when emerging from a heavy sleep, but he had his faculties with him almost at once, and was ready for action.

"What is it?" he asked, in a whisper.In like low tones Blake told him, and then the three boys, after making sure by a cautious observation that neither of the suspected men was in sight, went out into the corridor and to the deck.

It was quite dark, for all unnecessary lights were dimmed, but there was a new moon, and the stars were bright, so that objects were fairly clear. On either side could be dimly observed the black shapes of the convoying destroyers.

"Where are they?" asked Joe, in a whisper. "The traitors!"

"I don't know—we'll have to look," was Blake's answer. They looked along the deck, but saw no one, and were about to turn to the other end of the craft when a figure stepped out from the shadow of a boat and sharply challenged them.

"Who are you—what do you want?" was asked.

It was one of the ship's crew assigned to night-watch. Blake knew him slightly, having, at the man's request one day, showed him something of the workings of a moving picture camera.

"We came up looking for two gentlemen who have the staterooms opposite ours," Blake answered, resolving to "take a chance" in the matter. "Lieutenant Secor and Mr. Labenstein," he added. "Have you seen them?"

"Yes; they came up to get a bit of air, they said," answered the sailor. "I saw them a little while ago. You will find them up near the bow. Do not show a light, whatever you do, and light no matches. If you wish to smoke you must go below."

"Thanks, we don't smoke," Joe answered, with a low laugh. "But we'll be careful about lights."

"All right," answered the sailor. "We have to look out for submarines, you know," he added. "This is the worst part of the danger zone."

The boys moved forward like silent shadows, peering here and there for a sight of the two figures who had come up a little while before them, with evil intentions in their hearts they had no doubt. Even now there might be flashing across the dark sea, from some hidden vantage point on the ship, a light signal that would mean the launching of the deadly torpedo.

"There's no doubt, now, but the Frenchman is a traitor," whispered Joe to Blake. "I have been positive about that German being a spy ever since I've seen him, but I did have some doubts regarding Secor. I haven't any now."

"It does look bad," admitted Blake.

"I wish I'd smashed him with my auto, instead of waiting for him to smash me," remarked Charlie. "He's a snake, that's what he is!"

"Hush!" cautioned Blake. "They may be around here—any place—and hear you. I wish we could see them."They moved along silently, looking on every side for a sight of the two conspirators, but there were so many shadows, and so many places where the men might lurk, that it was difficult to place them. The sailor, evidently, had had no suspicions, thinking that Blake and his chums had merely come up to be with the two men.

"What are you going to do when you do see them?" asked Joe of his chum.

"I don't know," was the whispered answer. "First, we've got to see them, then we can tell what to do. But where in the world are they?"

Somewhat at a loss what to do, the boys paused in the shadow of a deckhouse. They were about to emerge from its dim protection when Charlie plucked at Blake's sleeve.

"Well?" asked the moving picture boy, in a low voice. "What is it?"

"Look right straight into the bow, as far as you can see," directed Macaroni. "Notice those two moving shadows?"

"Yes," answered Blake.

"I think that's our men," went on Charlie.

"Yes, there they are," added Joe.

It was evident, after a moment's glance, that the two men who had so silently stolen from their rooms were together in the bow of the steamer, or as far up in the bow as they could get. The deck was open at this point, and, leaning over the side, it would be easy to flash a signal on either beam. The lookout on the bridge was probably too much occupied in sweeping the sea ahead and to either side of the ship to direct his attention to the vessel itself.

"Come on," whispered Blake to the other two. "We want to hear what they are saying if we can, and see what they're doing."

Silently the boys stole forward until they could make out the dim figures more clearly. There was no doubt that they were those of Secor and Labenstein. And then, as the boys paused, fearing to get so close as to court discovery, they saw a little light flash.

Three times up and down on the port side of the bows went a little flash of light, and then it suddenly went out.

"My electric light," whispered Blake in Joe's ear.

"But I thought you said it would burn out!"

"I hope it has. I think——"

From one of the figures in the bow came a guttural exclamation:

"The infernal light has gone out!"

"So?" came from the other.

"Yes. It must be broken. Let me have yours, Herr Lieutenant. I have not given the signal in completeness, and——"

"I left my light in the stateroom. I'll go and——"

But the lieutenant never finished that sentence. Across the dark and silent ocean came a dull report—an explosion that seemed to make the Jeanne tremble. And then the sky and the water was lighted by the flashing beams of powerful lights.

"What was that?" gasped Joe, while from the crouching figures in the bow came exclamations of dismay. "Are we torpedoed?"

"I fancy not," answered Blake. "Sounded more like one of the destroyers made a hit herself. I think they set off a depth charge against a submarine. We'll soon know! Look at the lights now!"

The sea was agleam with brilliant radiance.