This was the state of affairs towards the end of January. The police were completely baffled; Inspector Whyland, although he still favoured the theory he had evolved in the picture-house, had failed to find any evidence upon which he could act. He hardly knew whether to attribute Mr. Copperdock’s story of his meeting with the black sailor to pure hallucination, or to an attempt to divert suspicion from himself. In either case, it could be made to fit in with the theory that he had murdered Richard Pargent under the influence of what the psychologists called an imitative complex. Whyland redoubled his activities, and a most accurate watch was kept upon Mr. Copperdock’s movements. A month had elapsed since the murder of Richard Pargent when Mr. Jacob Martin, the prosperous wine merchant of the Barbican, opening his morning post in his comfortable office, came upon a typewritten envelope, marked “Private and Confidential.” He ripped it open with the paper cutter which lay upon his desk, and unfolded the letter it contained. It also was typewritten, on plain paper. Only the signature “John Lacey” was in ink.