Curtain: Poirot's Last Case

Poirot suspects that a single person is involved in five previous murders. In all cases, there was another clear suspect. Four of these suspects have since died (one of them hanged). In the case of Freda Clay, who allegedly gave her aunt an overdose of morphine, there was too little evidence to prosecute. Poirot calls on his old friend, the recently widowed Hastings, to join him at Styles Court in solving this case. Poirot alone sees the pattern of involvement. Using a wheelchair due to arthritis, and attended by his new valet Curtiss, Poirot will not share the name of the previously unsuspected person, using X instead.

X is among the guests with them at Styles. The old house is now a guest hotel under new owners, Colonel and Mrs Luttrell. The guests know each other, with this gathering initiated when Sir William Boyd-Carrington invites Dr Franklin and his wife to join him for a summer holiday stay. Hastings' daughter Judith accompanies Dr Franklin as his research assistant. The five prior murders took place in the area, among people known to this group. Elizabeth Cole tells Hastings that she is a sister of Margaret Litchfield, who confessed to the murder of their abusive father in one of the five cases. Margaret died in Broadmoor Asylum, and Elizabeth is stigmatised by the trauma.

Three incidents occur in the next few days that show the imprint of X. First, Hastings and others overhear an argument between the Luttrells. Shortly afterwards, Luttrell wounds his wife with a rook rifle, saying he mistook her for a rabbit. Mrs Luttrell recovers, and the incident has a good effect on their marriage. Next, Hastings is concerned that his daughter Judith spends time with Major Allerton, a married man. While Hastings and Elizabeth are out with birdwatcher Stephen Norton, Norton appears to see something through his binoculars that disturbs him. Hastings assumes it has to do with Allerton. When his attempts to persuade Judith to give Allerton up merely antagonise her, the worried father plans Allerton's murder. He falls asleep while waiting to poison Allerton and is relieved he took no action when he awakes the next day. Last, Barbara Franklin, wife of Judith's employer, Dr Franklin, dies the following evening. She was poisoned with physostigmine sulphate, an extract from the Calabar bean that her husband researches. Poirot's testimony at the inquest – that Mrs Franklin had been upset and that he saw her emerge from Dr Franklin's laboratory with a small bottle – persuades the coroner to return a verdict of suicide.

Norton appears to still be concerned over what he saw days earlier when out with Hastings and Cole. Hastings advises Norton to confide in Poirot. They meet in Poirot's room. That night, Hastings is awakened by a noise and sees Norton going back into his bedroom. The next morning, Norton is found dead in his locked room with a bullet-hole in the centre of his forehead, the key in his dressing-gown pocket and a pistol nearby.

When Hastings tells Poirot that he saw Norton return to his room the previous night, Poirot says it is flimsy evidence, not having seen the face: the dressing-gown, the hair, the limp, can all be imitated. Yet there is no man in the house who could impersonate Norton, who was not tall. Poirot dies of a heart attack within hours. He leaves Hastings three clues: a copy of Othello, a copy of John Ferguson (a 1915 play by St. John Greer Ervine), and a note to speak to his longtime valet, Georges. After Poirot is buried at Styles, Hastings learns that Judith has all along been in love with Dr Franklin. She will marry him and leave to do research in Africa. When Hastings speaks to Georges, he learns that Poirot wore a wig and that Poirot's reasons for employing Curtiss were vague.

Four months after Poirot's death, Hastings receives a manuscript in which Poirot explains all. X was Norton, a man who had perfected the technique of which Iago in Othello (and a character in Ervine's play) is master: applying just such psychological pressure as is needed to provoke someone to commit murder, without his victim realising what is happening. Norton had demonstrated this ability, with Colonel Luttrell, with Hastings, and Mrs Franklin. Poirot intervened with sleeping pills in Hastings' hot chocolate that night, to avert a disastrous rash action. Ironically, Hastings had unwittingly intervened in Mrs. Franklin's plan to poison her husband, by turning a revolving bookcase table while seeking a book to solve a crossword clue (Othello again), thus swapping the cups of coffee, so Mrs Franklin poisoned herself. Poirot could not prove this. He sensed that Norton, who had been deliberately vague about whom he had seen through the binoculars, would hint that he had seen Franklin and Judith, to implicate them in the murder of Mrs Franklin, not inadvertent suicide as it was. This explains Poirot's testimony at her inquest, to ensure the police would stop their investigation.

Given his very weak heart, Poirot conceives that he must end the string of murders by killing Norton. Poirot invites Norton to his room for hot chocolate. At their meeting, he tells Norton what he suspects and his plan to execute him. Norton, arrogant and self-assured, insists on swapping cups. Anticipating this move, Poirot had drugged both cups, knowing that he had a higher tolerance for a sedative dose that would incapacitate Norton. Poirot moves the sleeping Norton back to his room using the wheelchair. Poirot could walk all along, one reason he needed a new valet who was unaware of that for this last case. Then, being the same height as Norton, he disguises himself by removing his wig and false moustache, ruffling up his grey hair, donning Norton's dressing-gown and walking with a limp. Having Hastings establish that Norton was alive after leaving Poirot's room, Poirot shoots Norton, leaves the pistol on the table and locks the room with a duplicate key. Poirot then writes his story and ceases to take his amyl nitrite heart medicine. He cannot say it was right to commit murder, but on balance he was sure he prevented yet more instigated by Norton. His last wish for Hastings is typical for Poirot the matchmaker: he suggests that Hastings should pursue Elizabeth Cole.