"Follow me below," he whispered. "I'll do the talking. Agree with whatever I say and listen carefully to my every word."

The three friends obeyed.

Below they were ushered into what proved to be the commander's cabin.

An officer in the dress of a lieutenant commander of the German navy rose and greeted the boys' captor with a salute and an extended hand.

Their captor grasped the hand.

"Commander von Ludwig, I take it," said the commander of the vessel.

Von Ludwig bowed.

"The same, sir," he replied. "I have here a paper that gives me command of your vessel, sir. You are ordered to report to Berlin at once."

"I have been expecting you, sir," was the reply. "I shall leave at once, if your boatman is still near."

"I ordered him to await you," was von Ludwig's reply.

The commander of the German vessel glanced at von Ludwig's three companions.

"Your officers?" he asked.

"Yes. Your officers will be relieved in the morning."

"Very well, sir. Then I shall leave you. A safe and successful voyage to you, sir."

"The same to you, sir."

Von Ludwig, motioning to his companions to remain in the cabin until his return, went on deck with the departing commander. A few moments later the latter was being rowed ash.o.r.e. For the s.p.a.ce of several seconds, von Ludwig gazed after him, a peculiar smile lighting up his face as he murmured:

"If you only knew what a time I had getting the paper I just gave you, you would not be going so serenely about your business right now. Oh, well----"

He threw open his arms with a gesture and descended to his cabin.

"Now," he said to Jack, Frank and Harris, "the first thing we must do is to secure the crew and the officers of this vessel. The crew, I happen to know, numbers only ten men. There are two officers. We shall have to overcome them."

"And how are we going to work the ship, sir?" asked Jack.

Von Ludwig glanced at the lad sharply.

"You would be a better sailor, sir, if you would follow orders without question," he said sharply; then added more calmly: "However, I shall tell you, for I can see none of you trust me fully. I have my own crew of five men coming aboard within the hour."

"I beg your pardon, sir," said Jack.

"That's all right," said von Ludwig. "Now follow me."

The others did as ordered. Before a door not far from the commander's cabin von Ludwig stopped.

"In there you will find the first officer," he said

He motioned to Frank and Jack. "Get him and get him quietly."

The lads nodded their understanding and von Ludwig signalled Harris to follow him.

Jack laid his hand on the k.n.o.b of the door and turned it gently. The door flew open without a sound.

"Find the light switch, Frank," Jack whispered.

Frank's hand felt carefully over the wall.

"Turn it on when I give the word," said Jack. "I may need to see what I am doing."

"All right; but be careful, Jack."

Slowly Jack tiptoed across the room, where he could dimly see a form stretched across a bunk. Bending over the figure, Jack raised a hand and then called to Frank:

"Lights, Frank!"

Instantly, Frank threw the switch and then sprang forward to lend Jack a hand should it be necessary. But his a.s.sistance was not needed.

Jack's fist rose and fell once and the form in the bunk gasped feebly once and lay still.

"I don't like that sort of thing," said Jack, "but I suppose it had to be done. Help me bind him up and gag him. He's not badly hurt and will come round in a few minutes."

It was the work of but a few moments to tear the sheets into strips and to bind and gag the helpless man. Then Jack and Frank left the cabin.

At almost the same instant von Ludwig and Harris came from a second cabin.

"All right?" asked von Ludwig.

"All right, sir. And you?"

"Everything shipshape. Now for the crew. First, however," he said, addressing Jack and Frank, "don the clothing of these two officers. You shall be my second and third in command."

The lads returned to the cabin they had just quitted and stripped the prisoner. Jack donned the uniform, for the German was a big man. Then they hurried into the second cabin and performed a similar operation and Frank soon was attired in the uniform of a German lieutenant.

"Now," said von Ludwig, "have the crew report here and keep your guns ready."

Frank made his way aft, and in German, called:

"All hands forward!"

The crew came tumbling from their bunks and hurried forward, most of the men no more than half dressed. Jack, Frank and Harris, on either side of von Ludwig, confronted them.

"Men," said von Ludwig, "I am the new commander of this ship and we shall get under way immediately. Fearing that you will not always obey my commands, I have brought along these little persuaders."

A pair of automatics flashed in his hands and covered the ten sailors.

"Hands up!" he cried.