Plot summary
Superintendent Spence visits Poirot to ask him to find evidence that would forestall the execution of James Bentley, who has recently been convicted of killing his elderly landlady, Mrs McGinty, for a meager £30. All evidence points to his guilt, but something about Bentley's surly acceptance of his fate just doesn't sit right with the experienced Spence. Poirot agrees to go to the village of Broadhinny and investigate the murder. Taking a room in the Summerhayes' guest house, Poirot finds that Mrs McGinty often worked as a charwoman at various village houses. No one suspects otherwise in their initial talk to Poirot, most being satisfied that Bentley is guilty.
During the course of his investigations, Poirot discovers that, three days before the murder, Mrs McGinty took a clipping from a notorious Sunday newspaper, containing an article showing photos of females who had disappeared after being involved in decades-old criminal cases. She then wrote to the paper, claiming to have found a photo like one of the women, proving a villager was one of the missing women in disguise. However, her terrible spelling had caused the paper to dismiss her as a simple fame-seeker. Poirot and Spence, using the ages of people in the town, conclude that someone is either Lily Gamboll, who committed murder with a meat cleaver at only 12 years old, or Eva Kane, a governess who had had an affair with her employer, Mr Craig. Craig was later convicted and executed for killing his wife. After being acquitted as an accessory, a pregnant Eva had changed her surname to "Hope" and left the country. Some sources claim she had a child named Evelyn, and several women in the town are the right age to be Evelyn, as well.
Shortly afterwards, Poirot discovers an old sugar cutter with traces of blood on it in the Summerhayes' house; the house is never locked, and the hammer could have been easily accessible to anyone. In an attempt to flush out the murderer, Poirot claims to know more than he does, and is nearly pushed under an oncoming train, proving that the guilty party is still at large. Having acquired originals of the photos used in the article, Poirot shows them to the villagers at a gathering at wealthy Mrs Laura Upward's house. Mrs Upward claims to have seen the photo of Lily Gamboll, but refuses to say where.
Later, Poirot is contacted by Maude Williams, who had worked at an estate agent's with Bentley in another town before Bentley was laid off. She refuses to believe he is capable of murder, and offers to help Poirot. He accepts, and gets her to pose as a maid in the house of Mrs Wetherby, one of the houses Mrs McGinty cleaned. Poirot notices that Mrs Wetherby's daughter by her first marriage, Deirdre Henderson, is rather sulky and defeated, much like Bentley. Deirdre is also the only villager who, like Maude, believes in Bentley's innocence.
During the maid's night off, Mrs Upward's spoiled son, playwright Robin Upward, goes to the theatre with famed mystery writer Ariadne Oliver, whose novel he is planning to dramatize. When they return home, they find Mrs Upward strangled to death. She has evidently had coffee with her murderer, and the lipstick on a coffee cup and perfume in the air points to a woman having committed the crime. Mrs Upward had invited three people to her house that night: Eve Carpenter, Deirdre Henderson, and Shelagh Rendell. Only Henderson (Mrs Summerhayes) came, but she found the house dark, and left without speaking to anyone. Any of the three women could be someone from the photographs. Additionally, the postmistress's assistant, Edna (who is having an affair with the husband of Mrs McGinty's niece), saw someone with blonde hair enter the house; Carpenter and Rendell (who both refuse to cooperate with the police) are blonde, but Henderson is brunette.
A book is discovered in the Upward house with Evelyn Hope's signature written on the flyleaf, suggesting Mrs Upward was actually Eva Kane, further confusing the situation. Poirot then finds a photo in a drawer in the Summerhayes' house, and realizes it must be the photo Mrs McGinty saw. It is of Eva Kane, with the inscription of "my mother" on the back. Recognizing the handwriting, Poirot gathers the suspects together and abruptly accuses Robin Upward of the murders, startling him into a confession.
Robin Upward is Eva Kane's son, Evelyn Hope (at the time, the name Evelyn was still often given to male children); the real Robin Upward had died young, while Mrs Upward lived elsewhere. Too proud to be pitied as a childless widow, Mrs Upward took in impoverished young men to take Robin's place, although she treated them more as a patron would a protégé, and dropped them if they turned out less than satisfactory. Evelyn Hope had been the most successful son, and had been living with her at the time she moved to Broadhinny; he was assumed by most to really be her son Robin, although Mrs Summerhayes, herself an adopted child, deduced the truth. Mrs McGinty found the photo of Eva Kane while working at the Upward house, and assumed the photo was of Mrs Upward as a young woman.
Evelyn, realizing that any scandal would put an end to his use of Mrs Upward's money, stole the sugar cutter and killed Mrs McGinty before she could tell too many people of her discovery. He framed Bentley by stealing the £30, correctly assuming Bentley would panic and incriminate himself. The night of the party, Mrs Upward had recognized Eva Kane's photo as that of Evelyn's mother, whose backstory Evelyn had falsified to her. She wanted to confront Evelyn by herself, so she pointed to the photo of Lily Gamboll to put Poirot off the scent.
Evelyn suspected the truth; pretending to forget something the night of the play, he left Mrs Oliver waiting in the car and went back inside, killing Mrs Upward to inherit her money. He planted the evidence, and made the three calls in a disguised voice, to make it appear as if a woman had committed the crime. He later planted the photo at Mrs Summerhayes' house to incriminate her; however, Poirot had gone through the drawer a short time earlier, and the photo had not been in it then. It had been put in afterwards, and only Evelyn had been free to do so at the time in question.
Further revelations are also made. Eve Carpenter wanted to conceal her past from her aristocratic husband, which was why she would not co-operate in the investigation. Spence discovers that Shelagh Rendell has been receiving poison pen letters claiming her husband murdered his first wife. Poirot heavily suspects that it was Dr Rendell's neurotic wife, and not Evelyn Hope, who tried to push him under the oncoming train, afraid of the old scandal being raked up. Maude Williams turns out to be Maude Craig. Despite the jury deciding otherwise, both Maude and the police are convinced her mother was actually murdered by Eva Kane and not Mr Craig, who chivalrously took the blame since Eva was carrying his child. Maude was the blonde who was seen going to see Mrs Upward, as she had been trying to trace Eva Kane through Evelyn, knowing his true identity. However, Maude found Mrs Upward's body, realized she might be accused of murder, and left quietly. She admits this to Poirot, who agrees to keep it a secret and wishes her good luck in her life.
Deirdre Henderson is revealed to be mistreated by her stepfather and forced to care for her malingering mother; Deirdre has money of her own, left to her by her biological father, that they do not want to lose the use of. She also has some romantic feelings for Bentley, and he for her. Bentley is freed, though he is still too bewildered over events to show proper gratitude. However, Spence is convinced they have closed the case at last, much to Poirot's relief.
