Curtain recap

Hastings, a widower, returns to Styles, the country house where he first met Poirot, now a shabby guest house. Poirot is there, crippled and dying, and tells him that one of the residents is a murderer he calls X, who has been present at five deaths for which other people were convicted or blamed, and refuses to name the person. Hastings watches the household: the bickering Luttrells, the research scientist John Franklin and his invalid wife Barbara, the mild bird-watcher Norton, the plausible Major Allerton, and his own daughter Judith. Colonel Luttrell shoots his wife and calls it an accident; she recovers. Hastings, convinced Allerton means to ruin Judith, plans to poison him and falls asleep before he can. Barbara Franklin then dies of poison in her coffee, and the inquest calls it suicide. Norton hints that he has seen something through his field glasses and is found shot in his locked room. Poirot dies of heart failure days later. His posthumous manuscript reveals that Norton was X, an instigator who talked others into murder, and that Poirot, unable to prove anything, killed him and then let himself die.

Captain Arthur Hastings first met Hercule Poirot at Styles Court in Essex during the First World War, when Poirot was a Belgian refugee living in the village and Hastings was convalescing at the house; the poisoning of its mistress was the case that began their partnership. In the years that followed Hastings acted as Poirot's companion and chronicler through many investigations, argued with him about method, and was regularly wrong about the murderer. He married and went to live in the Argentine, and by the time of this book he is a widower with grown children, among them a daughter, Judith. Poirot has long since become a famous man and has grown old.

Hastings comes back to Styles, which is now a run-down guest house kept by Colonel Luttrell and his sharp-tongued wife. Poirot has taken rooms there and asked him to come. Hastings is shocked by his condition: arthritis has crippled him, he cannot walk, his heart is failing and he keeps a stimulant beside him. His mind is unaffected, and he explains why he is there. He has studied five entirely separate cases, in different places and years, in which somebody was convicted or generally held guilty of murder, and in each of them one particular person was present. That person he calls X, and X is at Styles now. Poirot flatly refuses to give the name, on the ground that Hastings could not conceal what he knew and that the knowledge would be dangerous. He wants Hastings to be his legs and his eyes, and to report what he sees without knowing what it means.

Hastings takes stock of the household. Dr John Franklin is working on the poisonous properties of a West African bean, assisted by Hastings's daughter Judith, who states unsentimental opinions about useless lives that disturb her father. Franklin's wife Barbara is an invalid who talks about being a burden, attended by Nurse Craven. Sir William Boyd Carrington, a wealthy and popular baronet, has arrived from a colonial governorship and is an old friend of the Franklins. Stephen Norton is a mild, stammering bird-watcher who lends people his field glasses and listens to their troubles. Major Allerton is an experienced philanderer whose attentions to Judith alarm Hastings badly. Elizabeth Cole is quiet and evasive about her family, and eventually admits to Hastings that her real name is different, and that her sister was convicted of killing their father and died in an asylum, one of the five cases Poirot has described. Meanwhile the Luttrells' marriage is played out in public, with Mrs Luttrell humiliating her husband in front of the guests night after night.

Colonel Luttrell, out with a rifle after rabbits, fires at a moving shape in the shrubbery and hits his wife. She is badly wounded but recovers, and the near tragedy transforms the marriage: she becomes gentle with him and he cheers up remarkably. Hastings, who was present, is uneasy about the conversation that preceded the shot. His own preoccupation is Judith. Convinced that Allerton is a practised seducer who means to ruin her and abandon her, and that nothing he says will stop it, Hastings comes to the conclusion that the only solution is to kill him, and prepares to do it with an overdose of Poirot's sleeping tablets dropped into a nightcap. He carries the plan almost to the point of execution and then falls into a heavy sleep and wakes to find the moment gone. In the morning he is appalled at himself. Poirot, when he speaks to him, is unusually severe about the danger of a man deciding to take a life.

Barbara Franklin's mood swings between despair and a strange gaiety; she talks about being an obstacle to her husband's career and about the African post he has been offered. On a warm evening the party takes coffee on the terrace and afterwards moves indoors, the cups standing for a time on a revolving bookcase table by the window. In the night Barbara Franklin is taken ill and dies, poisoned with the drug her husband extracts from the Calabar bean. The inquest hears evidence of her low spirits and returns a verdict of suicide while of unsound mind, which the household accepts with relief and which Poirot makes no attempt to disturb. Hastings is troubled by it: he remembers her talk of the future that evening, and it did not sound like a woman preparing to die.

Norton lets slip that while watching birds he saw something through his field glasses that startled him, and refuses to say what or who. He tells Poirot he will speak to him about it, goes up to his room that night, and is found in the morning shot through the exact centre of the forehead, the door locked and the key in his dressing gown pocket, so that the death is recorded as suicide. Poirot, who has been visibly weaker for days, says almost nothing about it, and within a short time his heart fails and he dies at Styles, with the ampoules that might have revived him out of his reach on the table. Hastings is desolate. Judith, who has been silent and unhappy throughout, tells him that she has never had the slightest interest in Allerton and that she loves John Franklin, and she leaves with him for Africa. Among Poirot's effects Hastings is given a copy of Shakespeare's Othello, and is told that a sealed manuscript addressed to him is to be delivered in four months' time.

The manuscript arrives and Poirot's last case is explained. X was Stephen Norton. He killed nobody with his own hands; he found the weakness in other people and worked on it with sympathy and suggestion until they did the killing, then stood aside while somebody else was convicted, which is why no charge could ever touch him. He had done it five times before, he brought Colonel Luttrell to the shot that nearly killed his wife, and he was at work on Judith. Barbara Franklin had prepared the poisoned drink for her husband; Poirot could not prevent the attempt but would not let it succeed, and the revolving table was turned so that she took the cup herself, a death for which he takes the responsibility. He also tells Hastings that his impulse to poison Allerton was Norton's doing, and that Poirot drugged his cocoa that night to stop him. Since nothing could be proved against a man who only talked, Poirot judged the case himself: his helplessness was in part assumed and he could walk when he chose, and he drugged Norton, went to his room, shot him precisely through the forehead, locked the door from outside with a duplicate key and returned. Having done it, he refused to let his own life be saved, left his heart medicine out of reach, and submitted to the same judgement, leaving Hastings the whole account.

Four months after Poirot's death, Hastings receives the manuscript Poirot left for him. X was Stephen Norton. Norton never committed a murder with his own hands: he studied people, found the crack in each of them, and by patient sympathetic suggestion brought them to the point of killing, then withdrew and watched somebody else be blamed. He had done it in the five earlier cases, he pushed Colonel Luttrell to the shot that nearly killed his wife, and he was working on Judith. Barbara Franklin had prepared a poisoned drink for her husband; Poirot, who could not prevent the attempt and would not let it succeed, saw to it that the revolving bookcase table was turned so that she took her own draught, and he takes the responsibility for her death on himself. Poirot also reveals that Hastings's impulse to poison Major Allerton was Norton's work, and that he drugged Hastings's cocoa that night to stop him. Since nothing could be proved against a man who only talked, Poirot appointed himself judge: his helplessness was partly assumed, he could walk when he chose, and he drugged Norton's cocoa, went to his room in the night, shot him neatly through the forehead, locked the door from outside with a duplicate key, and returned. He then withheld the heart medicine that would have saved him, submitting to the same judgement he had passed on Norton, and leaving the whole account to Hastings.