"Can it be some wild animal?" asked Helen.

"With boots on? I bet!" scoffed Bob.

It was pitch dark. The three crouching together in the corner of the
little chamber were not likely to attract the attention of this marauder,
if all went well. But their hearts beat fast as the rustle of the
approaching footsteps grew louder.

There loomed up a man's figure. It looked too big to be either Tom or
Ralph, and it passed on with an assured step. He needed no lamp to find a
path that seemed well known.

"Who--what----"

"Hush, Helen!" commanded Ann.

"But he's going right to the cave--and he carried a gun."

"I didn't see the gun," whispered Ann.

"I did," agreed Bob, squeezing Helen's arm. "It was a rifle. Do you
suppose there is any danger?"

"It couldn't be anybody hunting us, do you suppose?" queried Helen, in a
shaken voice. "Anybody from the house?"

"Preston!" exclaimed Ann.

"How would he know the way to get into this tunnel?" returned Bob. "Come
on! let's spy on him. I'm worried now about Tom and the others."

"You don't suppose anything has happened to Ruthie?" whispered Helen. "Oh!
you don't believe _that_, Bobbins?"

"Come on!" grunted the big fellow, and took the advance.

They were careful of their own footsteps over the loose stones. The person
ahead acted as though he had an idea he was alone.

Nor did they overtake him until they had passed the open crack in the roof
of the tunnel. Somebody laughed in the cavern ahead--then the girls all
shouted.

The marauder stopped, uttering an astonished ejaculation. Bob and the two
girls halted, too, but in a moment the person ahead turned, and came
striding toward them, evidently fleeing from the sound of the voices.

Ann and Helen were really frightened, and with faint cries, shrank back.
Bob _had_ to be brave. He leaped forward to meet the person with the
rifle, crying:

"Hold on, there!"

"Ha!" exclaimed the other and advanced the rifle until the muzzle touched
Bob Steele's breast. The boy was naturally frig