But before his finger could press the trigger his wrist was seized in a strong grasp from behind and the weapon was twisted from his hand.  Whirling angrily Davis looked into the face of Frank, who was smiling quietly.

“What’s the meaning of this?” demanded the latter.

Davis face turned dark with rage.

“I’ll show you,” he cried, and struck a vicious blow at the lad.

But Frank had been prepared for some such move and stepped back quickly.

Davis missed.

Frank realized that this was neither time nor place to settle his grievance with Davis, so he took the simplest way out.  His hand flashed to his belt and his revolver came to a level.

“That’s enough,” he said sharply.  “One step forward and I’ll shoot, so surely as my name is Frank Chadwick.”

There was no mistaking the menace in the lad’s tones, and growling to himself, Davis dropped his hands.  Then, still muttering and keeping at some distance, he slunk away, hurling over his shoulder: 

“I’ll get you for this yet.  Remember that.”

Frank did not take the trouble to reply, but instead approached Jack and Lord Hastings.

“How are things, sir?” he asked.

“At a standstill,” replied Lord Hastings.  “The German is withholding his fire, but there are still people on the liner.  If he will restrain his impatience for a few minutes everything will be all right.”

“Perhaps he will, sir,” said Jack hopefully.

“I trust so.  It will be better for all concerned.  Everything ready, Frank?”

“All ready, sir.  You’re sure No. 2 torpedo has the range?”

“Perfectly.  It will reach the enemy’s bridge at its present angle.”

“Could I have a look, sir?” asked Frank.

For a brief moment Lord Hastings hesitated, then stepped aside and motioned Frank to his place at the periscope.

“Give the command to fire if anything happens,” instructed Lord Hastings.

Frank nodded, and placed his hand on the signal button, at the same time peering into the periscope.

Above everything was perfectly plain.  The lad could see that the captain of the liner and some passengers still remained aboard; and, a short distance away, he saw the German submarine, with her commander standing upon the bridge, watch in hand.

Suddenly the German’s watch closed with a snap.  Frank drew a sharp breath, for he realized what was coming.  Slowly the German officer’s hand moved upward.  Frank divined that he was about to give the signal to fire a torpedo at the defenseless vessel.

Frank’s heart leaped into his mouth; and he pressed the little button beneath his finger.  And once again the signal board on the U-16 glowed red: 

“Fire!”

CHAPTER XVII.

AN ARGUMENT SETTLED—­TEMPORARILY.

There came a sharp, metallic click; and after it the silence of death aboard the U-16 for a brief second while Lord Hastings took Frank’s place.