“They’re coming back?” asked Helen, doubtfully.

“Hush!” commanded Ann again.  “Whoever it is, he has no light.  It can’t be Ruth.”

Much heavier boots than those the girl of the Red Mill wore now rattled over the loose stones.  Ann pulled the other two down beside her where she crouched in the corner.

“Wait!” she breathed.

“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 frightened—­how could he help being?  But he showed pluck.  He did not move.

“What do you want in here?  Who are you?” asked Bob, quietly.

“Goodness me!” gasped the other, and dropped the butt of his rifle to the ground.  “You sure did startle me.  You’re one of those boys staying with the Tingleys?”

“Yes.”

“And here’s a couple of the girls.  Not Ruth Fielding?”