Emma Lewin told us that she had been with Mrs. Fitzroy for over three years. Last night she had gone out as usual about six o'clock. She had left by the back door and had taken the key with her. She always did so. She returned just before ten, and had gone straight upstairs to take off her hat and jacket. She always did this before going in to see whether her mistress required anything. "Was the dining-room door shut when you went upstairs?" I asked. "Yes." "You did not go by the garden gate last night?" "No. I never go that way. The gate is never used." "Did Mrs. Fitzroy have many visitors?" "None to speak of. Not half a dozen people have called upon her since I have been here. I believe she had no relations. Once or twice a week she would be out all day, and occasionally she has been away for a night or two." "Where has she gone on these occasions?" I asked. "I do not know." "And her correspondence--was it large?" "She received very few letters," the servant answered; "whether she wrote many, I cannot say. I certainly didn't post them." "Did she use the telephone much?" "She gave orders to the tradesmen sometimes, and I have heard the bell ringing occasionally. You see, the kitchen is a basement one, and the bell might often ring without my hearing it." "Did your mistress smoke?" Quarles asked suddenly. "No, sir." "How do you know she didn't?" "I have heard her say she didn't agree with women smoking. Besides, when doing the rooms I should have found cigarette-ends." "That seems conclusive," said Quarles. "Yesterday was Wednesday, your night out?" "Yes, sir." "Is Wednesday always your night out?" "It is." "From six to ten?" "Yes; it is a standing arrangement; nothing ever interferes with it." "Very interesting," said the professor. "Now, of course you know what your mistress was wearing when you left her alone in the house last night?" "A brown dress with----" "I don't want to know," Quarles interrupted. "But I want you to go to your mistress's room and find out what hat and coat and what kind of boots she put on last night. She wouldn't be likely to go out dressed as you left her. You had better go with the young woman, Baker." He spoke in rather a severe tone, and, when the girl had left the room with the constable, I asked him if he suspected her of complicity in the affair. "My dear Wigan, as yet I am only gathering facts," he answered, "facts to fit theories. We may take the following items as facts: Mrs. Fitzroy did not smoke. She had few visitors. She received few letters. Once or twice a week she was out all day. The servant's night out is Wednesday. Yesterday, being Wednesday, a taxi waited for a considerable time in Melbury Avenue. The driver has brought his fare to Melbury Avenue on previous occasions." "And the theory?" I asked.