He did not call encouragement to Frank, for he wished to get aboard the plane, if possible, before the men could stay him.

The two Germans rushed Frank simultaneously, and bore him back in the plane. At the same instant, Jack, unmindful of danger that might lurk aboard and thinking only of Frank's danger, laid hold of the plane and climbed aboard. Then he stood erect and shouted:

"Come on, you cowards! Here's the other one!"

CHAPTER XI

DAWN--AND A NEW ENEMY

The two Germans, just about to throw Frank overboard, turned quickly at the sound of this new voice. They wasted no time.

"At him!" cried one, and leaped.

The other sprang after him.

Jack, with his feet wide apart and arms extended, braced himself to receive the shock; and when it came he was ready. Frank, in the meantime, sank down in the plane almost unconscious, for one of the Germans had all but choked the life from him.

As the first German sprang, Jack met him with a straight right hand blow to the face and the man reeled back. The second, seeing the fate of his companion, dived for Jack's legs and seized them, pulling the lad down.

Jack felt out with his left hand and encircled the German's neck. Then he squeezed. The German gasped for breath as his wind was shut off. His hand searched his belt and presently flashed aloft with a knife. Jack saw it. Releasing his hold on the man's throat, he seized the knife arm with his left hand and twisted sharply, at the same time driving his right fist into the man's face.

There was a sharp snap and a cry of pain. The knife fell clattering to the deck of the plane. Jack, very angry, rose to his feet, stooped over, and picking up the German as though he had been a child, heaved him overboard.

"So much for you!" he muttered.

He stepped across the body of the second German to Frank's side and stooped over him. Gently he raised his chum's head to his knee.

Frank's eyelids flickered and directly he opened his eyes.

"How do you feel, old man?" asked Jack.

Frank struggled free from his chum's grip and sat up. He shook his head once or twice and then rose to his feet.

"I'll be all right in--Look out!" he broke off suddenly.

He dodged. But Jack, not realizing the import of Frank's words, remained still. He felt something hot sear the lobe of his ear.

Wheeling abruptly, the lad saw the German whom he had first knocked unconscious facing him with levelled revolver--the weapon was Jack's own, which he had left behind when he swam to the enemy's aeroplane.

The German faced him with a smile.

"Hands up!" he commanded.

But Jack, with a few drops of blood trickling from his ear, suddenly became very angry. He objected to being shot at from behind.

"Put down that gun!" he commanded in a cold voice. "Put it down before I kill you!"

The German was struck by the menace in the lad's tones, and for a moment he hesitated and the revolver wavered. Then he braced and brought the weapon up again.

But that moment of hesitation decided the issue. In spite of the fact that the revolver was pointed right at him, and that only a few feet away, Jack took a quick step forward.

The German fired. Jack swerved a trifle. The bullet plowed through the sleeve of his shirt and touched the skin; but that was all.

Again the man's hand tightened on the trigger, but he never fired again. Jack's powerful left hand seized his wrist and twisted the revolver from it Then, still grasping the wrist, the lad wheeled on his heel. The German left the spot where he had been standing as though pulled by a locomotive. He was lifted high in the air and, as Jack gave a jerk and then released his hold, the man went sailing through the air and dropped into the sea with a loud splash.

And at the same moment the intense darkness was shattered. The first faint streak of dawn showed in the east.

Jack sat down. Frank did likewise.

"That settles that," said Jack, briefly. "Now we had better get away from here. We haven't any too much time."

Frank, without a word, took his place at the wheel.

"Feel fit?" asked Jack.

Frank nodded, though he felt terribly faint.

"Sure you can make it?" Jack continued.

"Yes," replied Frank.

"Well, I just wanted to know," said Jack, "because here comes a German torpedo boat."

Frank was startled. He turned in his seat, and there, not a mile and a half away, was a ship of war. She was flying the German flag and was making directly for the spot where the British hydroplane rested.

"By George! Won't we ever get out of this?" the lad muttered.

"We won't unless you hurry," said Jack.

"But those two Germans. Won't they be picked up and give the alarm?"

"One of 'em won't," said Jack, grimly, "and I feel pretty safe about the other, too. Let's get up in the air."

Frank tinkered with the motor and took a firm grip on the wheel. But the hydroplane did not move.

"Something wrong," said Frank, quietly.

"What?" demanded Jack.

"Something wrong with the motor. It won't work."

Frank had bent over and was examining it carefully.

Came a shot from the German torpedo boat.

"If we don't get out of here pretty quick," said Jack, quietly, "we won't get out at all."