"All right," said Frank, "it sounds easy; but how?"

"Well, that doesn't make any difference. We've got to do it."

"And the moment we have gone our absence will be discovered, the Germans will know the fleet has been warned and the attack will be given up," said Frank. "And we don't want anything like that to happen.

It will be the first time the Germans have mustered up courage enough to come out and give battle. We don't want to frighten them off."

"We don't want to let them sneak up on a part of our fleet unguarded, either," declared Jack.

"Of course not. You say we must give the warning. We'll try, of course.

But first, why not let's put all the aeroplanes except the one we want out of commission?"

"By Jove! a good plan! We'll do it."

"Exactly," said Frank. "Then there is still another thing."

"What is that?"

"Why, we want the instructions that fellow carries," and Frank waved a hand in the direction of the German leader. "He was kind enough to let us know he has them. We'll have to take them away from him."

"Say!" exclaimed Jack, "you've laid out quite a job for us, haven't you?"

"It's got to be done," declared Frank.

"Well, all right, but we shall have to be careful."

"Right you are," Frank agreed, "one little slip and the whole thing will be spoiled."

"Then there must be no slip," said Jack, quietly

"I agree with you there. Now the question arise? as how the thing may best be done."

"We'll have to wait until they're all asleep," said Jack.

"You forget the sentinels won't sleep," said Frank.

"No, I don't; and they will be the first disposed of. They are not looking for enemies from within, you know. You walk up to one and I'll walk up to the other. We'll be challenged when we get close, of course.

Then it will be up to us to silence those fellows before they can make an outcry."

"We'll try it. Then what?"

"Then we'll come back and put the airships out of commission as carefully as possible."

"That's easy enough. All we have to do is to let out the 'gas.'"

"Next we'll have to go through the commander's pockets without arousing him."

"That's more difficult, but I suppose it can be done."

"Next we'll have to get our hydroplane to the water. Fortunately, we came down closer to the sea than the others. We should be able to do that without awakening the sleepers."

"Then," said Frank, "we climb in and say goodbye, eh?"

"That's it."

"All right. We'll work it that way then. It's as good as any other. Now we'll keep quiet until we are sure everyone is asleep."

Their plans thus arranged, the lads became quiet. They said not a word as they waited for sleep to overcome the Germans, but gazed out quietly over the dark sea.

CHAPTER IX

THE PLAN WORKS--ALMOST

"Time to get busy."

It was Frank who spoke. All was quiet among the sand dunes. The commander of the Germans had laid down upon the ground, some distance from the others, half an hour before. Snores from various points announced that most of the men were sleeping soundly.

Jack and Frank got to their feet

"Careful," said Jack as they separated. "Remember, don't give your man a chance to let out a cry."

Frank nodded in the darkness and walked slowly toward the sentinel he had selected to silence. Jack moved in the other direction.

As Jack came within a few yards of his prey, the man raised his rifle and commanded:

"Halt!"

"It's all right," said Jack. "I couldn't sleep and it was lonesome back there. I want company."

The German lowered his rifle.

"It's lonesome here, too," he said. "Wish you had been selected for my job."

"I wouldn't have minded it tonight," said Jack, approaching closer.

The German reached in his pocket and produced a pack of cigarettes. He extended the pack to Jack.

"Have one?" he invited.

Jack accepted a cigarette.

The German produced a match. He laid his rifle upon the ground as he struck the match upon the leg of his trousers.

It was the moment for which Jack had been waiting.

Quickly his revolver leaped out. In almost the same instant he reversed it and before the German realized what was about to happen he brought the b.u.t.t down on the man's head with great force.