"Frank!" cried Jack in warning, but it was too late.

"The vanishing submarines, eh?" repeated the stranger. "So you have given yourselves away. Who but a German spy would be here seeking word of the vanishing submarines?"

"But I tell you——" began Jack.

"Silence," thundered the officer. "You have betrayed yourselves, and that is enough. I give you my word you shall be shot in the morning."

"Oh, I guess not," replied Frank with a laugh. "I guess Lord Hastings will be able to get us out of this mess."

"Lord Hastings?"

"Why, yes, we happen to serve under him; that's all."

"Tell it to the marines," replied the man with sarcasm. "I am not asking you to admit anything, for I know enough now."

"Oh, all right," said Frank.

"Climb into my boat," ordered their captor.