I looked into her big, questioning eyes, a harsh suspicion laboring in my mind, but could read nothing in their mysterious depths--only I wondered anew at my questioner's beauty. The grotesque idea momentarily possessed me that, were the bloom of her red lips due to art and not to nature, their kiss would leave--though not indelibly--just such a mark as I had seen upon the dead man's hand. But I dismissed the fantastic notion as bred of the night's horrors, and worthy only of a mediaeval legend. No doubt she was some friend or acquaintance of Sir Crichton who lived close by. "I cannot say that he has been murdered," I replied, acting upon the latter supposition, and seeking to tell her what she asked as gently as possible. "But he is--Dead?" I nodded. She closed her eyes and uttered a low, moaning sound, swaying dizzily. Thinking she was about to swoon, I threw my arm round her shoulder to support her, but she smiled sadly, and pushed me gently away. "I am quite well, thank you," she said. "You are certain? Let me walk with you until you feel quite sure of yourself." She shook her head, flashed a rapid glance at me with her beautiful eyes, and looked away in a sort of sorrowful embarrassment, for which I was entirely at a loss to account. Suddenly she resumed: "I cannot let my name be mentioned in this dreadful matter, but--I think I have some information--for the police. Will you give this to--whomever you think proper?" She handed me a sealed envelope, again met my eyes with one of her dazzling glances, and hurried away. She had gone no more than ten or twelve yards, and I still was standing bewildered, watching her graceful, retreating figure, when she turned abruptly and came back. Without looking directly at me, but alternately glancing towards a distant corner of the square and towards the house of Major-General Platt-Houston, she made the following extraordinary request: "If you would do me a very great service, for which I always would be grateful,"--she glanced at me with passionate intentness--"when you have given my message to the proper person, leave him and do not go near him any more to-night!" Before I could find words to reply she gathered up her cloak and ran. Before I could determine whether or not to follow her (for her words had aroused anew all my worst suspicions) she had disappeared! I heard the whir of a restarted motor at no great distance, and, in the instant that Nayland Smith came running down the steps, I knew that I had nodded at my post. "Smith!" I cried as he joined me, "tell me what we must do!" And rapidly I acquainted him with the incident. My friend looked very grave; then a grim smile crept round his lips. "She was a big card to play," he said; "but he did not know that I held one to beat it." "What! You know this girl! Who is she?"