"Well, then, I'll be going," the detective said, strutting across the room, with his little round belly protruding like that of an insect. "You can always find me at the hotel down here, if I'm in this part of the country. Just ask for me and I'll show up."

Canfield was turning to depart with the detective when Will motioned to him to remain. The caretaker turned back with a surprised look.

Will waited until the door had closed on the detective before speaking. Even then, he went to the door and glanced down the passage.

"Something exciting?" smiled the caretaker, noting the boy's caution.

"Yes," Will answered, "there's something exciting. Tommy and Sandy disappeared during the night."

"Disappeared?" echoed the caretaker.

"Yes," George cut in, "there was some talk of their visiting the mine just before we went to bed, and we are of the opinion that they went down the shaft shortly after we fell asleep, and failed to find their way to the surface again. We are considerably alarmed."

"I should think you would be!" replied the caretaker. "In the first place, the Labyrinth mine bears the right name. There are old workings below which a stranger might follow for days without finding the way out."

"Then we'll have to organize a search for the boys," George suggested.

"Besides," continued Canfield, "there are things going on in the mine which no one understands. I have long believed that there are people living there who have no right to take up such a residence."