Five Little Pigs

Sixteen years after Caroline Crale was convicted of fatally poisoning her husband Amyas, her twenty-one-year-old daughter Carla Lemarchant is given a letter; in it, the late Caroline claims to be innocent of the murder. Carla asks Hercule Poirot to reinvestigate the case; he does, and establishes that, on the day of the murder at the Crales' home, there were five other people present. Poirot dubs these "the five little pigs" – stockbroker Philip Blake, amateur chemist Meredith Blake (Philip's brother), Caroline's young half-sister Angela Warren, Angela's governess Cecilia Williams, and Amyas's painting model Elsa Greer. The police investigation found that Amyas had died of coniine poisoning, and Caroline confessed to stealing coniine from Meredith's lab, as she had been contemplating suicide. She had later brought a cold bottle of beer to Amyas, and both the police and the jury assumed she had poisoned the beer because Amyas was openly having an affair with Elsa.

Poirot interviews the five other suspects, noting that none has an obvious motive, and that Caroline's half-sister Angela is the only one who believes Caroline was innocent. He assembles the five, along with Carla and her fiancé, at Meredith Blake's house, and reveals the truth. Caroline was innocent, but chose not to defend herself because she believed Angela had committed the murder. Although Angela had handled the beer bottle, she had added nothing to it before her sister took it to Amyas. Caroline later assumed that her sister had added something to the beer as a prank, accidentally causing Amyas's death. When they were children, Caroline had thrown a paperweight at Angela, blinding her in one eye and scarring her face; Caroline had suffered from guilt ever since, and believed that sacrificing herself for Angela was a way to atone for her sin.

Poirot reveals the murderer was Elsa Greer. She had taken Amyas' promises to marry her seriously, unaware that he was merely lying to keep her from leaving until his "masterpiece" painting was finished. She overheard Amyas reassure Caroline that he was not going to divorce her, felt betrayed, and wanted revenge. She had seen Caroline take the poison from Meredith's lab, so she took it from Caroline's room and put it in a glass of warm beer that she gave Amyas. When Caroline later brought him a cold bottle of beer, he commented that "everything tastes foul today" after drinking it; this remark had shown Poirot that Amyas had taken the nasty-tasting coniine before Caroline brought him the beer.

Poirot's explanation solves the case to the satisfaction of Carla and her fiancé. He plans to present his findings to the police, though he admits the chances of a posthumous pardon for Caroline or a murder conviction for Elsa are slim, due to the lack of physical evidence. As she leaves, Elsa contends that Amyas and Caroline escaped her revenge, and that she, now living an empty life, is the one who really "died".