nd escape."

"Then one of us had better go to the mouth of the cave and either stop
him, or else be there to give the alarm when he tries to get out,"
proposed Andy. "I'll go."

"No, I think we'd better stick together," suggested his brother. "That
man is too dangerous for one of us to tackle alone. We may catch up to
him any moment now, and I hope he'll give in, and tell us what we want
to know."

Without the portable electric lights which they each carried it would
have been impossible for the Racer boys to have found their way about
the cave. They marveled how it was that the mysterious man could
follow the windings and turnings in the dark, but, as they learned
afterward, he had been in the cave before.

Back and forth, up and down, here and there, like following some
will-o'-the-wisp went the boys. At times they thought they had lost
the object of their pursuit, but again they would hear him hurrying on
ahead of them.

"Hold on a minute!" suddenly exclaimed Frank, when he had led the way
down a steep descent. "I don't like this."

"Like what?" asked Andy, in some alarm.

"This chase. That man knows what he's doing and we don't. If he
wanted to he could have been out of this cave a dozen times or more,
yet he's staying in and leading us on. He has some object in it, and I
don't mind confessing that I'm afraid of it."

"How do you mean afraid?"

"I think we may come to some harm. He fairly enticed us in here and
now he's playing with us as a cat does with a mouse. I'm going to stop
and go back to the entrance."

"Well, perhaps you're right," admitted Andy, and it was quite an
admission for him, as he was always willing to take more risks than was
his brother. "We'll stand still a few minutes and see what happens."

They remained there, quiet in the darkness. For a time not a sound
broke the stillness. Then, with startling suddenness came a hail:

"Well, why don't you catch me?"

"Catch me?" repeated the echoes, and there followed a mocking laugh.

"Here he is!" cried Andy. "Off to the left."

"No, the right," insisted Frank. "Over this way."

"All right," agreed Andy, and he followed his brother.

Hardly had he spoken than there rang throughout the cave a dull,
booming sound. It seemed to shake the ground.

"He's exploded something!" cried Frank, coming to a halt. He flashed
his electric torch around, but could see nothing. He and his brother
were in a low, rock-roofed passag