"Hallowe'en Party" is a mystery novel by Agatha Christie, published in 1969. The story revolves around a young girl named Joyce Reynolds, who confesses to witnessing a murder in the past, only to be found drowned in a tub at a Halloween party. The case is taken up by the famous detective, Hercule Poirot, who is determined to get to the bottom of the mystery.

The novel opens with Mrs. Ariadne Oliver, a famous detective novelist, seeking the help of her friend Hercule Poirot in solving the murder mystery of Joyce Reynolds. Joyce had confided in Mrs. Oliver about seeing a murder in the past, but she had dismissed it as a mere imagination. However, with Joyce's murder, Mrs. Oliver is convinced that the girl's claim was true and that the killer is still at large.

As Poirot delves deeper into the case, he discovers a web of deceit and lies that extend far beyond Joyce's murder. The party where Joyce was found dead is attended by a group of people, each with their own secrets and motives. Poirot is assisted in his investigation by Inspector Rudge, who is initially skeptical of Poirot's methods but eventually comes to admire his skill and intuition.

As Poirot unravels the clues, he discovers that the killer is using the Halloween party as a cover-up for the murder. The investigation leads them to a shocking discovery about the true identity of the murderer, and Poirot is forced to use all his wits to bring the culprit to justice.

The novel is a classic example of Agatha Christie's mastery of the mystery genre. It is filled with intricate plots, red herrings, and unexpected twists and turns. The characters are well-developed, and the setting of the Halloween party adds to the suspense and mystery of the story.

In conclusion, "Hallowe'en Party" is a thrilling murder mystery that will keep readers on the edge of their seats until the very end. Agatha Christie's clever plotting and skillful characterization make this novel a must-read for mystery fans.