disappears. Poirot stages a party where he demonstrates how the poisoned glasses were substituted by the murderer while everyone's attention was on the victim. He then receives a telegram from Mrs De Rushbridger, a patient at Strange's Yorkshire sanatorium, who arrived on the day Strange died. Poirot and Satterthwaite go to meet her, but find that she has in turn been murdered. Learning that Cartwright's servant, Miss Milray, is hastily heading to Cornwall, Poirot follows her to find out why. Upon his return, Poirot assembles Cartwright, Satterthwaite and Egg, eventually denouncing Cartwright as the killer. Cartwright wants to marry Egg, but already has a wife who resides in a lunatic asylum. As he cannot divorce her under British law, he decided to conceal this knowledge by murdering Dr Strange, his oldest friend and the only one who knew about the marriage. After his party, Cartwright convinced Strange to let him assume the role of his butler as a joke, and then poisoned him during his party and planted the nicotine cutting on Manders after tricking him into being at Strange's home. He falsified Ellis's blackmail letters, then travelled to Monte Carlo the day after to establish his alibi. The first murder was a dress rehearsal for the second to test whether the glass could be switched unseen, and the victim was selected at random. The only safe guests were Cartwright; Strange, who disliked cocktails; and Egg, to whom Cartwright gave a safe glass. Mrs De Rushbridger was used by Cartwright as a red herring to distract from Strange's behavior towards "Ellis", and he killed her to divert suspicion and prevent her revealing her ignorance of the case. Poirot reveals that the nicotine came from rose spray distilled by Cartwright at an old tower near his Cornwall residence; the equipment was found by him when Miss Milray went to destroy it. His suspicions about Cartwright were based on several facts; Cartwright was the most likely to have poisoned the cocktail, his passport book shows his return to England to play Ellis, Miss Milray's actions were motivated by a secret love for her employer, Miss Wills noted Cartwright's similarity to Ellis and was spirited away by Poirot to protect her, and the telegram supposedly from Mrs De Rushbridger was addressed to Poirot when she knew nothing of his involvement. Cartwright flees, but Poirot says that he will "choose his exit" of public