With caution the boys began to look around them.
"Look!" cried Frank in a low tone.
He bent down and from the rocky floor picked up a big bunch of keys.
"Auto keys," came from Joe.
"Yes, and all different. I suppose they have all the keys necessary to unlock any car."
"More than likely."
Near the keys they found a dark coat and a cap.
"I guess the keys dropped out of that coat," remarked Frank.
"Looks like it." Joe's gaze traveled to a spot back of the coat. "Look, a wig!" he exclaimed.
"That shows they go out disguised."
"It sure does. Say, we're getting to the bottom of this mystery!"
"I hope so."
The boys explored the underground chamber, but found nothing of further interest.
"So we were right, after all," Frank said. "Gus Montrose is mixed up with the auto thieves."
"He probably discovered these caves in the first place, and saw how they could be used for concealing stolen goods. Perhaps this place was used by smugglers long ago."
"Probably. They are natural caves, and it's
