With a nervous movement, entirely foreign to him, Dr. Priestley rose from his chair and stood facing the door. Harold, with a queer feeling of expectation, walked towards it and opened it. In the hall stood Inspector Hanslet, handing his coat and hat to Mary.

“Good evening, Mr. Merefield, I thought I’d look round and see if the Professor had any information for me,” he said. “May I see him?”

“Yes, come in by all means,” replied Harold, with a sudden sense of relief. “But I shouldn’t stay too long, if I were you. He’s rather tired and nervy tonight.”

Hanslet nodded, and Harold led the way into the study. “It’s Inspector Hanslet, sir,” he said.

The Professor appeared to have entirely recovered his usual equanimity. “Ah, good evening, Inspector,” he said blandly. “I half expected that you would be round this evening. I am very glad to see you.”