Tom whirled about.  The old instinct of the man who lives much in the open, telling him danger is close at hand, was stirring at the roots of his hair.  But he was just a trifle too late.  As he faced about, a form shot out of the cave and Tom, totally unprepared for attack, was bowled over.

As he fell he let out a great wordless cry, thinking to warn Frank and Roy Stone.  Then the butt of a revolver descended on his head.

CHAPTER XXIII

THE TABLES TURNED

“What was that?” asked Frank, turning to Roy Stone, as the airplane bearing Jack and Bob on their romantic adventure dwindled in the darkening sky.  “I thought I heard a shout.”

“Guess you did,” said Stone.  “I heard it, too.  It came from the cave.”

Both turned to stare upward toward the distant cave.  There was no sign of movement.  Only the dim bulk of the rock obscuring the entrance could be distinguished.  They looked at each other, a nameless fear stirring at their hearts.  Then Frank shook himself and laughed.

“Pshaw,” said he, “this lonesome place seems spooky.  I know what it must have been.  It must have been Tom shouting a farewell to the fellows.”

“Reckon you’re right,” said Stone, brightening.  “Sure, that must be it.  Well, let’s go back.  We’ll be starting in a couple of hours, if all goes well.”

“All right,” said Frank, reaching to pluck one of the oil flares out of the ground.

Stone halted him.  Again he looked anxiously toward the cave.

“Let’s not take the torches,” said he.

“Why not?”

“Just playing a hunch,” said Stone.  “I have the feeling that all may not be well up at the cave.”

Frank dropped his voice unconsciously, as if fearing eavesdroppers in that lonely spot.

“To tell you the truth,” said he frankly.  “I feel the same way.  I say!  I have an idea.  Let’s edge out of the light without hurry, not toward the cave, but out that way,” pointing in the direction taken by the airplane.  “We’ll put our hands up to our eyes and pretend to be watching the sky for the airplane’s flight.  It would be natural for us to want to get beyond the light of these torches, if we were trying to follow the boys with our eyes.”

“That’s the ticket,” said Stone, and the two put Frank’s plan into execution.

Beyond the light cast by the torches they paused.  Darkness had descended now, in truth.  Not even the shadowy bulk of the big rock before the entrance to the cave could be distinguished.

“Maybe we’re making ourselves nervous over nothing,” said Stone.  “I feel kind of foolish.  After all, what could happen?  That old cowman pal of yours looks pretty capable.”

“He is, too,” said Frank.  “Just the same, I feel we ought to be cautious.  If Tom’s all right when we reach the cave, well and good.  But if he isn’t------”