Mr. Ludgrove shook his head. “Now, this is strictly between ourselves, Inspector,” he said. “I make an invariable practice of taking a walk every evening, as soon as my clients give me the opportunity. This evening I went out soon after eight, and walked in the direction of Hyde Park. As it happened, I was returning past the Cambridge Arms, when I saw a figure which was unmistakably that of Mr. Copperdock leave the entrance of that house. I hastened my steps to overtake him, when suddenly he stopped, shouted, and after a moment or two, set off in the direction of Edgware Road. I could not imagine what was the matter, since but for us two the road was deserted as far as one could see for the mist. I was within twenty or thirty yards of him, and I certainly saw no black sailor.”

It was Inspector Whyland’s turn to smile significantly. “It does not altogether surprise me to learn that Mr. Copperdock suffers from hallucinations,” he said.