"It must be very late," Bobby said.
Katherine shivered.
"Half-past two. I looked at my watch. The same time as last night."
With a gesture of resolution she led the way into the corridor. Bobby shrank from the damp and musty atmosphere of the narrow passage.
"Why do you come, Katherine?" he asked.
"I have to know, as I had to know last night."
Graham raised his hand and knocked at the door which again was locked on the inside. The echoes chattered back at them. Graham knocked again. With a passionate revolt Katherine raised her hands, too, and pounded at the panels. Suddenly she gave up. She let her hands fall listlessly.
"It's no use."
"Howells! Howells!" Graham called. "Why don't you answer?"
"When he boasted to-night," Katherine whispered, "the murderer heard him."