"Well, West," I said, taking a card out of my case, and handing it to him, "if you ever see that lady again, and can find out who and what she is, and where she lives, I'll give you a present--say twenty pounds." "Twenty quid!" the man echoed with a whistle. "I'd like to touch the oof, sir, and you bet I'll keep my weather eye open." "As soon as you've found her, let me know, and the money is yours. You understand that's a bargain." "Right you are, sir. I'll do my very best." "If you only knew the driver of the cab she took after we parted you might, perhaps, learn something." "That's just what I'm thinking," he said. "The man who drove her was, I believe, an old fellow that we know as `Doughy' but I'm not at all sure. However, as soon as I set you down I'll go and find him. A driver is difficult to recognise if he wears another overcoat, you see. That's why I'm not certain that it really was `Doughy'." By the sharp descent of the roadway I knew that we were already in Essex Street, and a few moments later I had paid the man West and was ascending the stair to my own chambers. The enlistment into my service of this man, the only person who had seen the mysterious Edna, was, I congratulated myself, a very shrewd and clever commencement of the investigation which I intended, at all hazards, to carry out. Indeed, my only means of tracing her was through the intermediary of this one man, who had seen her and remarked upon her marvellous beauty. He seemed a sharp, witty fellow, and I therefore entertained every confidence in his efforts to earn the promised reward. He was now on his way to find his colleague, the old driver "Doughy," and if Edna had actually taken his cab I should, without doubt, soon be in possession of some information. Thus, with a light step and reassured feeling, I ascended the stairs, wondering what old Mrs Parker would say to my protracted absence, and how I should explain it to her. I took out my latch-key and opened the door. As I entered the tiny lobby that served the dual purpose of hall and a place in which to hang coats, a startling sound broke upon my ears--the sound of a woman's cry. In an instant I drew back. Fresh mystery greeted me. I stood there rigid, speechless, aghast. CHAPTER SEVEN. THE MYSTERY IS INCREASED. The voice which greeted me was that of a woman surprised by my sudden entrance; and walking swiftly forward to investigate, I passed into my own dingy sitting-room. "I have a visitor, it seems," I exclaimed, stopping short. "May I not know your name?" There was no response. Instinctively I knew that the woman I had thus disturbed was still present in that room wherein I spent so many lonely hours. Her startled cry was sufficient to convince me that she was there for some secret purpose. What, I wondered, could it be? "Speak," I urged. "Kindly explain your business with me, and the reason of your presence here."