My first thought was not one of alarm for Adelaide Spanton--of course, I knew I could prevent the murder--but of profound sorrow that Miss Russell should have proved to be a woman so unspeakably wicked. I swore never to trust a woman’s face again. I had liked her face. Then I dwelt on the chance, the mere chance, my careless pronunciation, a lift-boy’s error, which had saved the life of the poor millionaire girl. And lastly I marvelled at the combined simplicity and ingenuity of the plot. The scoundrel upstairs--possibly Samuel Grist himself--had taken the cleverest advantage of Miss Spanton’s tendency to pseudo-angina. What could be more clever than to poison with the physician’s own medicine? Very probably the girl’s present attack had been induced by an artful appeal to her appetite; young women afflicted as she was are frequently just a little greedy. And I perceived that the villain was correct in assuming that nitro-glycerine would never be traced at a post-mortem save in the smallest possible quantity--just such a quantity as I had myself prescribed. He was also right in his assumption that the pure drug would infallibly kill in half an hour. I pulled myself together, and having surreptitiously watched Miss Russell into Suite No. 63, I followed her. When I arrived at the bedroom she was pouring medicine from a bottle; a maid stood at the foot of the bed. “I am just giving the second dose,” said Miss Russell easily to me. “What a nerve!” I said to myself, and aloud: “By all means.” She measured the dose, and approached the bed without a tremor. Adelaide Spanton opened her mouth. “Stop!” I cried firmly. “We’ll delay that dose for half an hour. Kindly give me the glass!” I took the glass from Miss Russell’s passive fingers. “And I would like to have a word with you now, Miss Russell!” I added. The maid went swiftly from the room. V. The old bald-headed lawyer had gone down to the hotel smoking-saloon for a little diversion, and we faced each other in the drawing-room--Miss Russell and I. The glass was still in my hand. “And the new doctor is so-so, eh?” I remarked. “What do you mean?” she faltered. “I think you know what I mean,” I retorted. “I need only tell you that by a sheer chance I stumbled upon your atrocious plot--the plot of that scoundrel upstairs. All you had to do was to exchange the bottles, and administer pure trinitrin instead of my prescribed solution of it, and Miss Spanton would be dead in half an hour. The three millions would go to the Australian cousin, and you would doubtless have your reward--say, a cool hundred thousand, or perhaps marriage. And you were about to give the poison when I stopped you.” “I was not!” she cried. And she fell into a chair, and hid her face in her hands, and then looked, as it were longingly, towards the bedroom. “Miss Spanton is in no danger,” I said sneeringly. “She will be quite well to-morrow. So you were not going to give the poison, after all?” I laughed.