“Harry!  Hazelton!” bawled Tom, with all the power in his lungs.

There was no answer.

“Jupiter!  You’ll have to land me, I reckon,” quaked Tom Reade.  “Drive her nose in—–­gently.  I’ll be ready to jump.”

“Be careful how you do jump,” warned Evarts.  “It’s mighty slippery on that wall tonight.”

Tom poised himself as the boat moved in close.  Then he took a light leap, landing safely.

Here the young chief engineer again brought his pocket flash lamp into play.  Closely he scanned the top of the wall all around where he knew he had left his chum.

But Harry was nowhere to be seen, nor, on the wet wall, could Tom find any signs of a scuffle, or any other sign that gave him a clue.

“Evarts, this is mighty mysterious!” groaned the young chief.

“Unless—–­” hinted the foreman.

“Unless what?”

“Perhaps Mr. Hazelton ran along the walltop to the shore.”

“He’d have hailed us, then, in passing, wouldn’t he?” choked Tom Reade.  “Besides, I had the light playing on this wall most of the way.  If he had run back we would have seen him, even if he hadn’t hailed.  And he couldn’t have run farther out to seaward.  Evarts, I’m downright worried.”

Tom Reade might indeed well be worried over the grewsome mysteries of this night of evil deeds.

CHAPTER IV

SOME ONE CALLS AGAIN

Half an hour later Tom Reade leaped ashore at the little pier.

“My orders, Mr. Reade.”

“They’re brief and concise,” Tom rejoined.  “You’re to cruise the length of the wall, especially farther out from shore.  Use your searchlight freely.  Keep the wall so guarded that no rascal can slip out there, either over the wall or by boat, and do any damage.  Mr. Evarts, the safety of the wall until daylight is your whole charge.”

“Very good, sir.  But I’m sure that nothing more will happen to the wall.”

“If anything does it will be up to you, Mr. Evarts,” Tom assured him grimly.  “I’ll hold you responsible.”

“I won’t let anything happen, Mr. Reade.  And I hope you find Mr. Hazelton all right.”

“He may be up at camp,” Tom answered, though in his heart he did not believe it.

Had Harry escaped whatever danger had menaced him, Tom knew very well that his chum, after appealing for help, would by some means have signaled his subsequent safety.

However, Tom started toward camp at a run.  He was wholly mystified.  The search in the neighborhood of the breach in the wall had been continued until its hopelessness had been fully demonstrated.  The search had also been continued over the water, for a possible clue to the mystery.

Though Tom ran, he felt himself choking, stifling.  Despite all his efforts to cheer himself the young chief engineer felt certain that his chum had mysteriously met his fate, and that brave, dependable Harry Hazelton was no more.