“I know the poison you speak of, certainly. The brother sold me a quantity of it. He professed it was all he had brought to England.” “He deceived you, then. In the next letter she described exactly where she kept the poison, in a chiffonier in her drawing-room within reach of the first caller. She boasted that she kept it under lock and key, but almost anyone could pick a lock like that, as even I could see. Of course, I knew from that moment that the poison was within my husband’s reach, and I felt sure he meant to take it. Why else should he have asked about it so particularly? What did it matter to him where it was kept, unless he wanted it himself?” “I quite agree with you,” said the specialist, seeing that he was expected to reply. “Now you see where I stood. I knew that my husband was capable of committing a murder, if he had anything to gain by it, and now I knew that he was actually scheming to obtain a poison that couldn’t be detected. I don’t think Mrs. Baker had an idea that her brother had parted with some to you. She wrote as though her bottle held all there was. And who was it that he was thinking of murdering? I couldn’t see anyone but myself.” “Mother!” The word burst from Sarah’s agonized lips. If she had retained any lingering softness for the dead man it must have expired in that cry. Her mother did not turn her head. “I had to defend myself. I couldn’t prevent him from taking the poison in any other way that I could think of. I went to Mrs. Baker’s house and stole the bottle.” “You were quite right,” the physician agreed again. “I had no difficulty. I took a bunch of all the keys I could find in the house, keys of wardrobes and drawers and boxes of different sizes, and went round to the Square. I walked up and down till I had seen a woman who looked like the mistress of the house come out, and then I knocked, and asked to be allowed to wait upstairs. I gave some common name.” She put her hand to her forehead. “That’s strange! I can’t remember the name. Well, almost the first key I tried opened the chiffonier and there stood the bottle just as she had described it I put it into my pocket and came away.” Whatever theory Sir Frank had formed as to the case, it had certainly not included this incident. He had thought it possible that after Weathered had carried off the bottle his wife had found it and taken it in turn from him. He had never conjectured that the feeble-looking woman had been brave and cool enough to checkmate her husband in advance like this.