Hallowe'en Party is a work of detective fiction by Agatha Christie and first published in the UK by the Collins Crime Club in November 1969 and in the US by Dodd, Mead and Company later in the same year. The UK edition retailed for twenty-five shillings. In preparation for decimalisation on February 15, 1971, it was also priced on the dustjacket at £1.25. The US edition retailed at $5.95.
The novel features her Belgian detective Hercule Poirot and the mystery novelist Ariadne Oliver. The novel’s concentration on child murder (with its possible sexual motivation), the irresponsibility of teenagers and the crisis in crime and punishment make it one of Christie’s most modern and unsettling novels.
In a return to the style of Poirot’s mysteries published in the thirties and early forties, the detective gathers information through a painstaking series of interviews. Elizabeth Whittaker gives him a crucial piece of evidence when she says that during the party Rowena Drake, apparently startled by something or someone she had seen in the vicinity of the door to the library where Joyce had been murdered, dropped and smashed a full vase of flowers. Other suggestive pieces of evidence include the fact that Lesley Ferrier had previously been suspected of forgery. Were Lesley and Olga working together to secure the inheritance? If so, why does Mrs. Llewellyn-Smythe’s cleaner confide to Mrs. Oliver that she had witnessed a genuine will that did indeed leave the entire fortune to Olga?
Poirot visits a sunken garden built for Mrs. Llewellyn-Smythe in an abandoned quarry, where he meets the beautiful young man who designed the garden: Michael Garfield. While there, he also meets the elfin Miranda Butler, a striking young girl who has befriended Michael and spends a great deal of her time in the Quarry Garden.
Joyce’s younger brother, Leopold, has been obtaining money from someone. Soon, however, he also falls victim to the murderer: drowned on the way home. Rowena, obviously very upset by his death, admits that it was Leopold that she had seen leaving the library. She had wrongly inferred that the boy had killed his sister: something that she could not bring herself to admit previously.
Poirot now has enough information to proceed and persuades the police to dig up an abandoned well in the Quarry Garden whose existence had been mentioned by Miranda. Within its depths are discovered the remains of Olga, who had been stabbed like Ferrier. Poirot sends to Mrs. Oliver to get Mrs. Butler and Miranda safely away from the village as soon as possible, but when they stop for lunch Miranda is abducted by Michael Garfield, who takes her to a pagan sacrificial altar where he clearly intends to kill her. He is only stopped by Nicholas Ransom and Desmond Holland, two teenagers who had been persuaded by Poirot to trail Miranda. Garfield commits suicide by swallowing the poison that he had intended her to drink.
Garfield, Olga’s secret lover, had been working with Rowena to secure her inheritance. The real will leaving Mrs. Llewellyn-Smythe’s fortune to Olga had been replaced with a forgery to the same effect produced by Lesley Ferrier. Both Ferrier and Olga had then been murdered, but the murder of Olga had been witnessed by Miranda, who told Joyce much later about it. Joyce, an inveterate fantasist, had made the story her own, and had convinced Rowena that it was Joyce whom she had suspected of watching on the night of the murder. Rowena had quickly drowned Joyce, later dropping the vase to explain why her clothing was so wet. Subsequently, Leopold had used what little he knew to blackmail Rowena, and had been himself murdered.
Garfield has participated in all this through a vain, narcissistic desire to construct another perfect garden with Rowena’s money on a Greek island that she has secretly purchased. Poirot’s final intuitive leap is his suspicion that the bond between Miranda and Garfield was a familial one: Judith Butler is not a widow, but is rather the mother of Garfield’s illegitimate daughter. His willingness to murder his own daughter in order to further his ambitions merely confirms the tremendous evil that Poirot has been able to uncover and defeat.
Robert Weaver in the Toronto Daily Star of December 13, 1969 said, "Hallowe'en Party...is a disappointment, but with all her accomplishments Miss Christie can be forgiven some disappointments...Poirot seems weary and so does the book.
Robert Barnard: "Bobbing for apples turns serious when ghastly child is extinguished in the bucket. The plot of this late one is not too bad, but the telling is very poor: it is littered with loose ends, unrealised characters, and maintains only a marginal hold on the reader's interest. Much of it reads as if spoken into a tape-recorder and never read through afterward.
Shopping website Amazon.com was much more enthusiastic in its review, stating: "The tension mounts until it explodes in a dazzling denouement, which is as logical as it is unexpected. Here is a novel that bears the unmistakable stamp of a gifted artist. The intricate puzzle, the unfaltering suspense, and the insight into those human passions that lead to murder."
The novel was first serialised in the weekly magazine Woman's Own in seven abridged instalments from November 15 - December 27, 1969 illustrated with uncredited photographic montages.
In the US, the novel appeared in the December 1969 issue of Cosmopolitan magazine.