“Lead the way, then, Tom,” said Jack, “because you know the route.  And be quick.”

Swiftly, yet withal cautiously, because the cave might be defended, they approached the big rock.  As they sidled around it, a gleam of light from the mouth of the cave at the rear of the rock fell athwart their path.  Involuntarily they drew back.

Then Jack brushed Tom Bodine aside and took the lead.  His repeater thrust before him, crouching, he entered the mouth of the cave.  A moment later his whisper came back: 

“Coast’s clear.”

But the others already were at his heels.

A hasty glance around revealed the first of the two chambers, which Tom had said the cave possessed, was luxuriously furnished and lighted by a powerful electric bulb enclosed in a huge frosted globe suspended from the middle of the roof.  There was no time for further investigation because Jack already was pushing on toward the heavy hangings at the rear covering the mouth of the second chamber, and the others clung to his heels.

Parting the hangings quickly, Jack threw his rifle to his shoulder.  Then he and his companions received their second big surprise.  The room was empty of human occupants.  But it, too, was brilliantly lighted.

And it was a radio broadcasting station.

To the trained eyes of the boys that much was apparent at first glance.  In one corner of the tremendous cave hummed the dynamo.  From it, of course, came also the electricity for the lights.  Before they could pursue their investigations, however, Tom Bodine, who had dropped back to the outer entrance, issued a warning hiss.  Then he darted across the outer room and joined them.

“Three of ’em,” he whispered.  “They’ll be here in a minute.”

“Good,” said Jack, taking command.  “We’ll give them a surprise.  These hangings are fastened to rings on a big pole up above us there, and they’ll slide easily.  Tom, you and Bob grab the hangings in the middle and be ready to pull them aside when I say the word.  Frank, you and I will stand here in the middle and keep them covered.”

All took their assigned positions as the sound of voices was heard at the outer entrance.  Jack peered between the two folds of the hangings and smiled with satisfaction.

“Let’s go,” he said.

The hangings flew aside.

CHAPTER XVIII

THE FIGHT IN THE CAVE

“Hands up, gentlemen,” ordered Jack, rifle to shoulder.

“And be quick about it,” added Frank, revolver extended.

Tom and Bob, the hangings disposed of, ranged themselves on either side of the pair.  Four weapons covered the group in the outer room.

The three men, who had advanced well to the center of the room, stared dumbfounded at these apparitions.  Then amazement gave place to anger, and one of the trio made a move as if to draw his revolver.