"He is undoubtedly the same," said Lord Hastings. "Also his story probably is true. I can vouch for the fact that he carries a number, and that he was recently in England."

"Will you and your men come aboard my vessel?" invited the young German.

"I should be pleased to have you look at this man Davis. I have him in irons."

"We shall be pleased," Lord Hastings accepted. "But first we must go below and tie up these English sailors. We don't want them to get away."

The young German bowed, and Lord Hastings, Frank, and Jack went below.

Here Lord Hastings called the men to him and in a few words explained the situation. The men consented to be bound and the three tied them up, for, as Lord Hastings said, it was just as well to keep up appearances.

Before returning on deck Lord Hastings also issued a few sharp commands to Jack and Frank.

"Just keep your nerve and everything will turn out all right," he said.

"But Davis," exclaimed Frank. "He is likely to betray us."

"Don't you believe it," said Lord Hastings. "Von Rosten doesn't trust him very much and Davis will be sharp enough to know it. That's why I want to appear to be doing him a good turn. Besides, it will throw both of them off the track."

"I see," replied Frank. "I wouldn't have thought of that, sir."

Lord Hastings again led the way on deck and informed the young German commander that they were ready to accompany him aboard his vessel. The latter motioned them into the small boat ahead of him.

Ten minutes later they were all seated in Captain Von Rosten's own cabin. The German summoned his first officer.

"Have the prisoner brought here," he commanded.

A few moments later, Davis, still in irons, stood before them. He gave an exclamation of surprise when he glanced at the three Englishmen, and all knew that he recognized them. Lord Hastings thought it would be well to get in the first word.

"I see you recognize us," he said sharply.

"Well, I guess I do," returned Davis. "You are----"

"Never mind who we are," interrupted Lord Hastings. "Enough for you to know that you almost spoiled everything."

"What's that?" demanded Davis. "I almost spoiled everything? Me?"

"Yes, you," returned Lord Hastings quietly. "You and the Baron Blosberg, with your impatience. I don't suppose you know that we carry numbers, eh?"

"I didn't know you did," replied Davis. "These other two here,"

indicating Jack and Frank, "I surmised did, or else I was fooled. But the last time I saw you you wore a British uniform and seemed to be perfectly at home."

"Fortunately for the rest of you," commented Lord Hastings dryly.

"Otherwise none of you would be here now."

Davis was apparently convinced.

"And did you have success?" he asked. "Have you solved the mystery of the----"

"Vanishing submarines?" interrupted Lord Hastings. "Yes. We have solved it."

Von Rosten sprang to his feet.

"Is it true?" he exclaimed eagerly. "The mystery has been solved?"

"It has," replied Lord Hastings quietly.

"And you can suggest means for overcoming it?"

"I can," replied Lord Hastings, and added: "At the proper time and place."

Von Rosten sat down and indicated Davis.

"Then you can vouch for this man?" he asked.

"Yes," replied Lord Hastings. "And I should be glad if you would release him. He is a traitor to his country and something of a bungler, but I can make use of him."

"Very well, sir," returned Von Rosten. "Then I shall turn him over to you."

"If you would be so kind," said Lord Hastings.

The German again summoned his first officer.

"Take the irons off this man," he commanded.

The first officer motioned for Davis to follow him.

"Return when you have been released," ordered Lord Hastings.

"Very well," said Davis.

He left the cabin.

"Now," said Lord Hastings to Von Rosten, "I would be glad if you could do a further favor for me?"

"Consider it granted if it is within my power," said the young German.

"Thanks," said Lord Hastings. "I should like to borrow half a dozen of your crew. As you know, I am short handed, and I have work to do."

The German hesitated, but only for a moment.

"Very well, sir," he returned. "I shall be glad to let you have them.

Would you also wish me to take care of your British prisoners?"

"Oh, no," replied Lord Hastings with a gesture. "They are hard workers, with a little urging," and he smiled. "They may come in very handily."

"As you please," replied the German.

A third time he summoned his first officer.