Suddenly the radio operator appeared on deck and hurried toward the bridge.  Jack stepped forward to meet him.  The lad took the message the operator passed him and read: 

    “S.O.S.  Pursued by submarine eighteen miles off Cape May light. 
    Am running south by west, but foe is gaining.  Capt.  Griswold,
    Ventura.”

“This,” said Jack quietly, “means that there is still another U-Boat to be reckoned with, but I had no idea they were operating so far out.  We’ll have to get busy.”

Jack looked at his officers with a slight smile on his face, then ordered:  “Shape your course due east, Frank.  Full speed ahead.”

CHAPTER XIV

THE U-87

As the Essex sped forward the radio operator from time to time picked up other messages from the Ventura.

“She’s headed directly toward us,” Jack explained to Frank.  “We should sight her within the hour.”

The Ventura was sighted in less, but under peculiar conditions.

“Ship on the starboard bow, sir,” sang the lookout forward.

A moment later the officers on the bridge sighted the vessel through their glasses.

“By George!  She seems to be standing still,” said Frank.

“So she does,” Lieutenant Hetherton agreed, “Wonder what’s the matter?”

“We’ll find out fast enough,” returned Jack quietly.

“Take the bridge, Mr. Chadwick,” said Jack.  “I’m going below to the radio room.”

“See if you can raise the Ventura,” he instructed the radio operator, a few moments later.

“Ventura!  Ventura!” went the call through the air.

There was no response.

“Try it again,” said Jack.

The operator obeyed.  Still there was no reply from the Ventura.

“Something wrong,” Jack muttered under his breath, “and still I saw no sign of a submarine.  Try ’em again, Wilkins.”

Again the radio operator sent the call flashing through the air: 

“Ventura!  Ventura!  Ventura!”

The instrument at Wilkins’ side began to click.

“Ventura replying, sir,” Wilkins reported.

“I hear him,” said Jack briefly.  “Let me get at that key, Wilkins.”

The operator sprang up and Jack took his place and strapped the receiver over his head.

“What’s the trouble, Ventura?” he clicked.

“Held up by submarine,” was the reply.  “U-Boat due east of us.  You can’t see her.  We sighted you just after we were boarded.”

“Then how does it come you are at the key?” Jack clicked.

“Broke away from captors on deck.  They are pounding at the door now.”

“Have they sighted us?”

“They hadn’t.  There goes the door, Good-bye.”

The flashes from the Ventura ceased.  Jack sprang up and turned the receiver over to the operator.

“Keep calling,” he said.  “If you pick the Ventura up again, let me know.  I’ll send a man so you can report to me through him.”