"Sure. I searched him carefully."
"All right. Then there is no need to search him again."
With his revolver he covered the lad while he backed from the little room.
"Good-by," he said, and jumping out quickly, slammed the door closed.
"Good-by," Hal called after him, without a tremor.
"When the water begins to rise," shouted Duval, through the door, "you may lose some of your nerve. I'd like to stay and hear you cry for mercy, but I have other work to do. However, my friend here will stay in the house, and I wouldn't be surprised if he didn't hear you upstairs."
To this Hal made no reply.
He now turned his attention to an examination of the room in which he was confined. The walls rose on all sides to a height of perhaps fifteen feet. This he had perceived while the door stood open, but inside now it was perfectly dark, except for a tiny stream of light that filtered in from below the walls, which failed to reach the floor by less than an inch.
The lad felt the walls carefully with his hands. They were perfectly smooth. He placed his fingers on the floor. It was dry.
He stood silent for some moments and then, becoming conscious of a strange sound, he again touched the floor with his fingers. They came away wet. Water was slowly trickling into the room.