In order that the exact truth should be made entirely plain to the reader and the mystery viewed in all its phases, it will be best for me to briefly record the main facts prior to entering upon any detail. The following were the circumstances exactly as I knew them. At twenty-five minutes to ten on the previous night--the night of January the sixth--I was at home in Albemarle Street, writing letters. Haines, my man, had gone out, and I was alone, when the telephone bell rang. Taking up the receiver I heard the cheery voice of Sir Digby Kemsley asking what I was doing. My prompt reply was that I was staying at home that night, whereupon his voice changed and he asked me in great earnestness to come over to his flat in Harrington Gardens, South Kensington, at eleven o'clock. "And look here," he added in a confidential tone, "the outside door will be closed at half-past ten and the porter off duty. I'll go down just before eleven and leave the door ajar. Don't let anyone see you come in. Be extremely careful. I have reasons I'll explain afterwards." "Right," I replied, and shut off. His request seemed just a little curious. It struck me that he perhaps wished to consult with me over some private matter, as he had done once before. Therefore, just before eleven I hailed a taxi in Piccadilly and drove westward past Gloucester Road Station, and into the quiet, eminently select neighbourhood where my friend lived. At eleven o'clock Harrington Gardens--that long thoroughfare of big rather gloomy houses, most of them residences of City merchants, or town houses or flats of people who have seats in the country--was as silent as the grave, and my taxi awoke its echoes until, about half way up, I stopped the man, alighted, and paid him off. Then, after walking a couple of hundred yards, I found the door ajar and slipped into the hall unobserved. Ascending the wide carpeted steps to the second floor, the door of the flat was opened noiselessly by the owner himself, and a few seconds later I found myself seated before a big fire in his snug sitting-room. My friend's face was grey and entirely changed, yet his manner was still as polished, cheery, and buoyant as ever. The flat--quite a small one, though very expensive as he had once remarked to me--was furnished throughout with elegance and taste. Upon its walls everywhere hung curios and savage arms, which he had brought from various parts of the world. The drawing-room was furnished entirely in Arab style, with cedar-wood screens, semi-circular arches, low, soft divans and silken rugs, which he had bought in Egypt, while, in contrast, the little den in which we were sitting at that moment was panelled in white with an old-rose carpet, rendering it essentially bright and modern. The tall, grey-bearded, elegant man handed me a box of Perfectos Finos, from which we selected, and then, throwing myself into a chair, I slowly lit up.