He shrugged his shoulders. Environment seemed to have an effect upon him, for his conversation was mostly by signs after we entered his room. Without a word he took finished work from various drawers and put it on the table for my inspection. I praised it, asked questions to draw him out, but failed to get more than a lift of the eyebrows, or an occasional monosyllable. It was not exhilarating, and as soon as I could I took my leave. "Come and see me again soon," he said, parting with me at the top of the stairs. "Thanks," I answered, as I went down, but I made no promise as I looked up at him silhouetted against the light from his open door. Little did I guess how soon I was to climb those stairs again. Next morning I was conscious that the night off, although not spent exactly as I had intended, had done me good. Some knotty points in a case I was engaged upon had begun to unravel themselves in my mind, and I reached the office early to find that the chief was already there and wanted to see me. "Here is a case you must look after at once, Wigan," he said, passing me the report of the murder of a man named Parrish, in Gray's Inn. Now, one of the essentials in my profession is the ability to put the finger on the small mistakes a criminal makes when he endeavors to cover up his tracks. I suppose nine cases out of ten are solved in this way, and more often than not the thing left undone, unthought of, is the very one, you would imagine, which the criminal would have thought of first. I fancy the reason lies in the fact that the criminal does not believe he will be suspected. I said nothing to my chief about my visit to Gray's Inn last night. Experience has shown me the wisdom of a still tongue, and knowledge I have picked up casually has often led to a solution which has startled the Yard. The Yard was destined to be startled now, but not quite in the way I hoped. When I arrived at Gray's Inn, a small crowd had collected before the entrance door of the house, as if momentarily expecting some information from the constable who stood on duty there--a man I did not happen to know. "That's him! That's him!" A boy pointed me out excitedly to the constable, who looked at me quickly. I smiled to find myself recognized, but I was laboring under a mistake. "Yes, that's the man," said a woman standing on the edge of the crowd. The explanation came when the constable understood who I was. "Both of them declare they saw the dead man in company with another man last night, described him, and now--" "I saw you with him," said the boy. "I never saw him with any one before, that's why I took particular notice." The woman nodded her agreement. "Better take the names and addresses, constable." "I've already done that, sir."