Miss Marple's nephew has paid for her to holiday at the Golden Palm resort on the Caribbean island of St Honoré, after a bout of ill health. She listens without much interest to the lengthy reminiscences of fellow guest Major Palgrave, but her attention sharpens when he recounts the case of a man who got away with murdering a series of wives. Palgrave produces a photograph of the alleged killer from his wallet and is about to show it to her when he looks over her right shoulder and abruptly changes the subject. Miss Marple notices several people in that direction. Next day, the maid Victoria finds Major Palgrave dead in his room. Miss Marple asks the local doctor, Dr Graham, to find the photograph Palgrave had mentioned, pretending it is of her nephew, but without success. Then, she interviews the others: Tim and Molly Kendal, the hotel owners; the Prescotts, a clergyman and his sister; Mr Jason Rafiel, an elderly tycoon who uses a wheelchair; Jackson, his valet; Esther Walters, his secretary; the American visitors Lucky Dyson and her husband Greg; and Edward and Evelyn Hillingdon. Señora de Caspearo, another holidaymaker, recalls Major Palgrave's supposed 'evil eye'; Miss Marple points out that in fact that he had a
glass eye. Victoria says that the blood pressure medication, Serenite, found in Major Palgrave's room after his death, had not been there earlier. That night, she is stabbed to death in the hotel grounds. Molly's behaviour has become increasingly erratic, and at one point she had been seen heading outside with a steak knife in her hand. Then, Tim finds Molly unconscious on the floor, apparently from an overdose of sleeping pills. With concerns about the Serenite medication, the police order Major Palgrave's body to be exhumed, and an autopsy reveals that he had been poisoned. At night, Miss Marple is woken by the sounds of a search party and is told that Tim had woken to find his wife missing. They find what seems to be her body in a creek, but it turns out to be Lucky; the two women resemble one another. Miss Marple has a revelation. She wakes Mr Rafiel and Jackson, calling herself
Nemesis, and together they go to the Kendals' house. There they find Tim offering Molly a drink. Miss Marple warns there is a deadly drug in it, and that Tim is the killer. Miss Marple explains that because of Major Palgrave's glass eye she had been confused about the direction he was looking when he saw the killer. Although apparently gazing over her right shoulder, he had in fact been looking towards her left, to where Tim and Molly were sitting. The story he had told about the serial killer was the story of Tim himself. Afraid of what Palgrave might disclose, Tim had killed him, planting the Serenite to make it look accidental, and had killed Victoria when she raised queries. He had been intending to kill Molly in order to marry Esther, whom he expected to inherit a significant sum from her employer Jason Rafiel, and had been putting
belladonna into her cosmetics to make her appear mentally unstable. Tim had asked his wife to meet him by the creek, but she had been distracted by an hallucination due to the belladonna and had wandered off. Tim saw Lucky and mistook her for Molly in the darkness. Molly takes on the running of the Golden Palm resort herself, with some financial help from Mr Rafiel. Miss Marple takes a flight home to England after her holiday. ==Principal characters==