There was one small window near where they were standing and the four boys crowded up to this, jostling each other in the attempt to be the first to see through the dingy pane.

“Hey!” whispered Jimmy in anguish, as Joe’s foot clamped firmly down upon his. “Quit parking on my toe, will you? There’s lots of room on the ground.”

Joe snickered derisively and that small sound came near to proving their undoing. For inside the cabin it happened that for a moment every one had stopped talking and in the silence Joe’s laugh was distinctly audible.

“Some one’s getting in on this,” they heard one of the voices say, as though its owner were nervous, yet was trying his best to hide his uneasiness. “Let’s take a look around, boys. You never can be too sure.”

The radio boys looked at each other in consternation. There was no time to get away, even if they had wanted to. And now that they were convinced there was crooked work going on in the shack, they certainly did not want to leave.

Bob flattened himself against the wall and motioned to his chums to do likewise. If the fellows found them and wanted to put up a fight, “well, they’d get their money’s worth, anyway.”

But it so happened that the lads were not discovered. The door of the shack was on the opposite side from them, and either the men were too lazy to search carefully or they were too confident of the obscurity of their meeting place. At any rate, they went to the door, looked around, and, finding no one within sight, evidently decided that they had been mistaken in thinking they had heard a suspicious noise and reëntered the shack without searching further.

“You’re crazy, Mohun,” the boys heard one of them remark, in an irritable voice. “You’re letting your imagination—and your nerves—run away with you.”

“Well, this deal is enough to get on anybody’s nerves,” was the grumbled reply, evidently from the person addressed as Mohun. “If we don’t put it across pretty quick I’m going to quit. I’ve told you too much delay would be fatal.”

The boys glanced at each other, and the relief they had felt at not being discovered was closely followed by huge excitement as they became more and more certain that they were on the verge of making an important discovery.