“I haven’t turned crazy,” replied Jack quietly.  “They are too many for us; that’s all.”

The other boat came alongside now and an officer stepped aboard the boys’ craft.

“Your weapons,” he said in perfect English.

“Then please step aboard my boat.  You shall be taken to Gravesend at once.”

“Gravesend!” echoed Jack.  “You couldn’t take us to a better place.  But if you are German, why should you take us there?”

“German,” repeated the man.  “You know we are English.  You are the German spies.”

“No such thing,” declared Frank, taking a hand in things.  “We are British officers and we thought you were German spies.  That’s why I fired at you.  We thought you were here to learn the secret of the vanishing submarines.”

“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.

The lads complied.

“Say,” said Frank, “this is Lord Hastings’ motorboat.  He told us not to lose it.  Tie it on behind and pull it along, will you?”

“We’ll pull it along all right,” replied their captor.  “Now the best thing you fellows can do is to keep quiet.”

The lads obeyed this gruff command, for they had nothing particular to talk about.

Half an hour later the motorboat docked at Gravesend and the boys were ordered to climb out, which they did, under the noses of their captors’ weapons.

“Where to now?” asked Frank.

“Where I tell you,” was the reply.

Jack was struck by a sudden thought.

“Will you tell me what time it is, sir?” he asked the leader of the party which surrounded them.

“As you ask in such a polite way, I shall do so,” was the reply.  “I wouldn’t tell this other fellow anything.  He’s too smart.”  He produced his watch, and after a glance at it, said:  “Five minutes to ten.”

“By George!” exclaimed Jack.  “And we were to meet Lord Hastings at the Lion Inn at 10 o’clock.”

“I can promise you’ll be at the Lion Inn at 10 o’clock,” replied the leader of the capturing party, “but whether you will find Lord Hastings there I can’t say.”