rled 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 Sto