Hallowe'en Party by Agatha Christie

At a village Halloween party, a teenager boasts that she once witnessed a murder and is later found drowned in a tub used for bobbing apples. A guest enlists Hercule Poirot, who digs into local gossip, past disappearances, and forgotten crimes to trace the truth behind the claim. His investigation reveals how an old killing, hidden motives, and a veneer of respectability converge, exposing the murderer lurking in plain sight.

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