Hallowe'en Party follows Belgian detective Hercule Poirot, who has been featured in countless Agatha Christie novels and short stories. One day, Poirot is summoned by his old friend, a crime novelist named Ariadne Oliver, who witnesses a disturbing scene at a Halloween party in the village of Woodleigh Common. At the party, Oliver hears a thirteen-year-old girl named Joyce Reynolds boasting about witnessing a brutal murder in her past. Most dismiss Joyce's claim because they think she wants attention. However, by the end of the party, Joyce is found dead in an apple-bobbing tub, her claims seemingly confirmed as a result of her death.
Ariadne is deeply disturbed by Joyce's murder and calls Poirot to investigate the matter. As Poirot delves deeper into the mystery, he learns of other deaths in the village that might be connected. Eventually, Poirot begins to link Joyce's claim with the unsolved murders of a local woman named Lesley Ferrier, and a teenager named Leopold Rice, years ago. He discovers that a man named Garfield killed each person to hide his paternity to a young woman named Miranda, who was due to receive a substantial inheritance.
Hallowe'en Party is told in Agatha Christie's typical style. The novel is very dialogue-heavy and told in a frenetic manner to rachet up its suspense. Not only that, Poirot is naturally a very important part of the novel. The story is built around Poirot's engaging but oftentimes enigmatic character. Readers see Poirot's intelligence firsthand, as he guides them through the mystery with his observations and witticisms.
Throughout the novel, Christie presents several characters as potential suspects in the murders. Each potential subject harbors their own secrets and motives. Additionally, Christie uses the setting of a seemingly innocuous village filled with people to portray the idea that darkness can lurk beneath the most ordinary and mundane of facades.
The aforementioned Ariadne Oliver is a metafictional nod by Christie to the crime genre. Oliver's character often provides humorous commentary on the nature of detective fiction and the process of crafting mysteries, reflecting some of Christie's own sentiments about the genre she so often writes in.
