Plot
The film is set in 1953 in St Mary Mead, the English village where Miss Jane Marple resides. A Hollywood production company arrives to film a costume drama about Mary, Queen of Scots and Elizabeth I with two famous movie stars, Marina Rudd and Lola Brewster. Marina is making a much-heralded comeback after a prolonged career absence (due to a mental health crisis after her son was born with severe brain damage). She and her husband, Jason Rudd, the film's director, arrive with an entourage. Marina is angry upon learning that her rival Lola is in the film. Lola and her husband, Marty Fenn, the film's producer, soon arrive.
The villagers attend a village fête at Gossington Hall, a large manor house, to welcome the film crew. During the indoor reception, Lola and Marina exchange insults while posing for photos. A devoted fan, Heather Babcock, bores Marina with a detailed story about once meeting her during WWII. She recounts leaving her sickbed to meet the glamorous star. Marina asks Jason to bring both her and Heather a cocktail. Heather suddenly dies after drinking it.
Her death is later attributed to a barbiturate overdose in the drink, though is believed that Marina was the intended murder victim. She receives anonymous death threats made from newspaper clippings, and her coffee on the film set, which she refused to drink, was spiked with arsenic.
Inspector Craddock, the Scotland Yard detective investigating the case is baffled. He asks his aunt, Jane Marple, for help. Marple is recovering at home after injuring her foot at the village fête. The suspects are Ella Zielinsky, Jason's assistant who is secretly in love with him and would like Marina out of the way, and the hotheaded actress, Lola.
The main suspect, Zielinsky, calls the murderer from a village phone box, threatening to expose them. She is then killed by a lethal nasal spray containing prussic acid instead of hay-fever medication.
Miss Marple, now recovered, visits Gossington Hall and inspects the murder scene. Helped by information that Cherry, her cleaning woman who was a server at the reception, has provided, Marple solves the mystery. However, another death has occurred at Gossington Hall that reveals the killer's identity: Marina Rudd, who has apparently committed suicide.
Miss Marple explains that Heather Babcock's story was Marina's motive. Years before, when Heather sneaked out to meet Marina, she unintentionally infected Marina with German measles, a mild disease that can be dangerous for a pregnant woman's foetus. Marina's child was born mentally handicapped. Hearing Heather cheerfully recount their earlier encounter, enraged and overwhelmed Marina who poisoned her. She then made it appear that she was the intended victim, crafting the false clues. Ella, who called various suspects from a phone box, accidentally guessed correctly, prompting Marina to murder her. Jason confesses to Miss Marple that he had poisoned his wife's hot chocolate to save her from being prosecuted, but the drink was untouched. Marina is nonetheless found dead, seemingly having poisoned herself.
