"Well, yes," he said. "I told him he would find some queer explosives there and a large number of swift torpedo boat destroyers, equipped with submarine nets. I told him that these made nightly raids into the Channel and the North Sea and thus disposed of the German submarines."

"And he believed it?"

"He seemed to. But that was the best I could do on short notice and knowing no more than I do of the matter."

"Well, it wasn't so bad," grinned Frank.

"I flatter myself that it could have been worse," returned Jack modestly.

They fell into a long silence, which was suddenly broken by Frank, who exclaimed anxiously:

"Say! Do you suppose that could have been a trap?"

"Trap?" repeated Jack. "What do you mean?"

"I mean, do you think Lord Hastings or some of the other British officers sent that man here simply to get evidence against us?"

"By Jove!" exclaimed Jack. "I never thought of that. Whew! Maybe I have gotten us into worse trouble than ever."

"If it was a trap, I guess you have," returned Frank glumly. "Yes, it was a good job you did, I don't think."

"Wait a minute, though," said Jack. "If it were a trap, it would be plainly evident we didn't know what we were talking about. That should be enough to let us out."

"Unless they believe we smelled a mouse and acted accordingly," returned Frank.

"Oh, well," said Jack, "there is no use worrying about it. We'll have to take what comes and that's all there is about it. Now, I'm going to rest a bit. When they come in, wake me up."

He leaned back in his chair and closed his eyes; and in the meantime Frank continued to turn events over in his mind.

Half an hour later Lord Hastings, the man who had led the party that captured the boys, a figure attired in the uniform of a colonel of infantry, and several others entered the room. The uniformed man Frank immediately took to be Colonel Masterson, and he was right. Frank nudged Jack and the latter opened his eyes. Then both boys got to their feet.

"So these are the German spies, eh?" said Colonel Masterson.

"That's not true," declared Frank hotly. "We are no more spies than you are."

"So?" said the colonel insinuatingly. "Then how does it happen you hold such friendly conversation with another man who is under suspicion?"

Frank's heart sank. So it had been a trap, after all.

"I can explain that, sir," said the boy, turning to Lord Hastings.

"I have no doubt of that," was the reply. "The question is, can you explain it satisfactorily?"

"Yes, sir, we can," interrupted Jack.

Here Colonel Masterson took a hand again. He spoke to Lord Hastings.

"What shall we do with them?" he asked.

"That, colonel, is for you to decide," was Lord Hastings' reply.

"Do you think it necessary to call a court martial?" continued the colonel.

"In view of the evidence we have, I should say not," returned Lord Hastings.

"And still," said Colonel Masterson, half to himself, "it seems to me that every man should be given a chance."

In the minds of the two boys now there was not the slightest doubt that they were in as perilous a situation as they had ever faced.

"Lord Hastings," said Jack quietly, "I a.s.sure you you are all mistaken.

However, we shall protest our innocence no longer, for I see it would be useless."

And then the two lads were treated to one of the surprises of their lives. Lord Hastings' stern expression gave way to a smile, and he strode quickly toward them and extended a hand to each.

"Surely," he said, "you didn't think I doubted you."

The lads were too stunned to say a word.

"I just wanted to teach you a little lesson," continued Lord Hastings.

"In the future, perhaps you will neither fall short nor go beyond your orders. I ordered you to Gravesend. You should not have gone beyond."

"But Davis, sir?" exclaimed Frank.

"As long as you were here, apparently prisoners," was the reply, "I simply used you to advantage. Davis is a German spy."

CHAPTER IV.

STRANGE WARFARE.

It was the following night.

Clad in heavy oilskins, Frank and Jack stood in the bow of the large, high-powered motorboat as it sped down the Thames in the darkness. Not a light was visible anywhere and it was impossible to see a yard ahead.

But in spite of this, the boat fairly flew over the water; for the strong hand of Lord Hastings was on the wheel and there was not a spot in the river with which he was not familiar.

"Whew!" said Jack, as he turned about to shield his face from the icy spray. "This is what I call taking a long chance, if you ask me."

"I should say so," replied Frank, raising his voice to a shout to make himself heard above the sound of the whistling wind. "Wonder how long we are going to keep this up?"

"Don't know," responded Jack. "But I don't feel very comfortable. This is too fast for me."

"Particularly when you can't see where you are going," Frank agreed.

Both became silent and peered into the intense darkness ahead.