Curtain

The novel is narrated by Captain Arthur Hastings, the longtime friend and collaborator of detective Hercule Poirot. Hastings travels to Styles Court, the English country estate where he and Poirot first solved a murder together decades earlier during World War I. The house has since been converted into a guest house run by Colonel Luttrell, a meek former military man, and his sharp-tongued wife. Poirot has summoned Hastings there, along with Hastings' daughter Judith, a serious and secretive young woman who works as secretary to Dr. John Franklin, a researcher studying tropical diseases. Franklin's wife, Barbara, spends most of her time in bed, claiming chronic illness.

Hastings is shocked by Poirot's condition. Once plump and fastidious, the Belgian detective is now thin, lined, and confined to a wheelchair by arthritis, dependent on his new valet, Curtiss, for basic care. Yet Poirot insists his brain remains unimpaired and reveals the real reason he has arranged the gathering: He is hunting a murderer. He presents Hastings with summaries of five seemingly unrelated murder cases in which the accused person's guilt appeared obvious. In each case, however, a single individual, whom Poirot calls X, was intimately connected to the crime without any apparent motive. X is now at Styles, Poirot says, and another murder will soon follow.

Poirot refuses to reveal X's identity, claiming Hastings' honest nature would betray the knowledge. The difficulty is that Poirot does not know who the intended victim will be, since X's method ensures no visible connection between X and the crime. Hastings must serve as Poirot's eyes and ears, identifying who fits the profile of a likely victim: someone against whom motive, opportunity, and a plausible suspect already exist.

Hastings surveys the household. The guests include Stephen Norton, a quiet bird-watcher; Sir William Boyd Carrington, a charismatic former colonial governor; Major Allerton, a charming but dissipated womanizer; Elizabeth Cole, a reserved woman; and Nurse Craven, Mrs. Franklin's attendant. Hastings instinctively suspects Allerton.

Several disturbing currents run beneath the surface. Judith passionately defends Margaret Litchfield, a woman who killed her tyrannical father, calling the act brave. In a group conversation about euthanasia, she argues that someone who loves a suffering person has a duty to end that person's life. Boyd Carrington, an old admirer of Barbara Franklin, dotes on her openly. Elizabeth Cole confides to Hastings that her real name is Litchfield and that she is Margaret's sister. She expresses tortured doubt that Margaret actually committed the murder. Hastings silently recognizes this may be true but cannot yet explain why.

The first crisis comes when Colonel Luttrell fires his rook rifle at what he believes is a rabbit and accidentally hits his wife in the shoulder. She survives, and Hastings witnesses genuine love between the couple at her bedside. That night, however, he realizes the incident fits X's pattern exactly: Colonel Luttrell would have appeared to be the obvious killer, just as in all the previous cases.

Hastings grows anxious about Judith's apparent attachment to Allerton. Norton privately warns him about Allerton's history, including a young woman who died by suicide after Allerton abandoned her. During a bird-watching outing, Norton sees something through his field glasses that visibly startles him, but he refuses to explain what he observed. Later, Hastings finds Judith coming out of Allerton's room and confronts her; she is cold and defiant. Driven to desperation, Hastings plans to poison Allerton by dissolving sleeping tablets in whisky. Before he can act, Poirot gives him a cup of chocolate secretly laced with sleeping powder, and Hastings falls asleep. He wakes the next morning, horrified. Poirot reveals the flaws in his plan and counsels him to trust Judith.

The central tragedy follows on a seemingly ordinary evening. Mrs. Franklin invites everyone to her room for coffee, which she prepares herself at a small revolving bookcase-table, with her husband handing cups from the other side. When the group steps onto the balcony to watch shooting stars, Hastings stays behind. Overcome by a memory of his dead wife, he swings the bookcase around to find a Shakespeare quotation. After a quiet end to the evening, Mrs. Franklin is taken violently ill during the night and dies the next morning of physostigmine poisoning, an alkaloid derived from Franklin's Calabar bean research.

At the inquest, Franklin testifies that a bottle of the alkaloid solution in his locked laboratory was found diluted with water; only he and Judith held keys. Poirot gives decisive testimony, claiming he saw Mrs. Franklin leave the laboratory holding a small bottle and that she had spoken to him about wanting to end her life. The jury returns a verdict of suicide. Privately, Poirot tells Hastings that Mrs. Franklin was murdered but insists the suicide verdict was necessary to shield Franklin and Judith, both innocent but vulnerable to suspicion because of their exclusive access to the laboratory.

Norton, still troubled by what he saw through his binoculars, consults Poirot privately. The next morning, Norton is found dead in his locked room, shot in the exact center of his forehead, a pistol in his hand and the key in his pocket. Hours later, Curtiss finds Poirot dead of heart failure. His amyl nitrate ampoules, the emergency heart medication, are not beside his bed.

Devastated and bewildered, Hastings opens Poirot's locked dispatch case and finds the X case files removed. Only two books remain: Shakespeare's Othello and the play John Fergusson by St. John Ervine, along with a note reading "Talk to my valet George." Judith reveals she is marrying Franklin and going to Africa. She was never interested in Allerton; her feelings were always for Franklin. Hastings visits George, Poirot's former valet, and learns that Poirot sent George away deliberately and wore a wig because his hair had fallen out.

Four months later, Hastings receives Poirot's posthumous manuscript, which reveals the full truth. X is Norton, whose unassuming appearance conceals the abilities of a master psychological manipulator. Like Iago in Othello, Norton never kills anyone directly. He identifies latent resentments and desires in others and, through careful suggestion, breaks down their moral resistance until they commit violence themselves. He manipulates Luttrell into firing at his wife, manipulates Hastings into nearly poisoning Allerton, and encourages Mrs. Franklin's scheme to poison her husband so she could marry Boyd Carrington. Mrs. Franklin dies only because Hastings inadvertently swings the bookcase-table, transposing the coffee cups so that she drinks the poisoned cup she had prepared for Franklin.

Poirot further reveals he can walk all along. He fakes his disability throughout his stay at Styles, sending George away because the perceptive valet would have seen through the deception and replacing him with the less observant Curtiss. On the night of Norton's death, Poirot drugs Norton's chocolate, wheels him to his room, and shoots him. He then dons Norton's checked dressing gown, removes his wig to reveal grey hair, and limps down the corridor so that Hastings sees the figure and assumes it is Norton. He locks the door from outside with a duplicate key, places the original in Norton's pocket, and returns to his room, where he moves his heart medication out of reach and allows himself to die.

In his final words, Poirot expresses moral uncertainty, acknowledging he has violated his own principles by taking a life. He argues Norton could not have been stopped by law and would have continued causing deaths. He urges Hastings to tell Elizabeth that her sister was another of Norton's victims and to find happiness with her. Reading the manuscript, Hastings realizes the truth was always before him: The bullet hole placed with perfect symmetry in the center of Norton's forehead bore Poirot's unmistakable signature of precision and order, "the brand of Cain" (224).