The Pyx, also known as The Hooker Cult Murders[6] and La Lunule[7] (French: The Moon), is a 1973 Canadian horror film directed by Harvey Hart and starring Karen Black, Christopher Plummer, Donald Pilon, and Jean-Louis Roux.

Based on John Buell's 1959 novel of the same name, it follows a Montreal police detective unraveling the mystery behind the death of a heroin-addicted prostitute who died under bizarre circumstances after falling from a building.

[8] Development of a film adaptation of Buell's novel dates back to 1964, when director Curtis Harrington expressed interest in directing a feature film for either United Artists or Columbia Pictures, and in which he considered casting several actors, including James Mason, Ursula Andress, Catherine Deneuve, and Orson Welles.

The Academy of Motion Picture Arts and Sciences holds the original 35 mm film and optical sound elements of The Pyx in their archive.

Upon Henderson's arrival, Keerson admits to having forsaken his faith for Satan and performed the Black Mass that culminated in Elizabeth's death.

"[9] Hart conducted interviews with Montreal police officers while developing the theme, specifically a homicide detective: "I really questioned him at length before we started shooting.

"[11] The film deliberately features a unique editing style that unfolds the dual character arcs of both Elizabeth and Sergeant Jim Henderson, the police officer investigating her death.

"[12] Director Curtis Harrington originally intended to direct a film adaptation of John Buell's 1959 novel The Pyx as early as 1964; his plans to develop the project are documented in his personal papers which are held by the Academy of Motion Picture Arts and Sciences.

[13] Harrington at one point pitched the film to United Artists, intending to cast James Mason and Ursula Andress, or a "similar calibre name.

[14] In a February 1967 interview, Mason stated he would be appearing as the lead police detective in the film, with Harrington directing the feature on location in Canada.

[13] Canadian director Harvey Hart, who had previously directed television episodes of Star Trek and The Alfred Hitchcock Hour,[15] ultimately went on to direct the film several years later without Harrington's involvement,[16] under executive producer Maxine Samuels,[4] who had primarily worked as a television producer for the Canadian Broadcasting Corporation.

[17] American actress Karen Black was cast in the lead role of Elizabeth Lucy, with Canadian actor Christopher Plummer portraying Sergeant Jim Henderson.

[20] Yvette Brind'amour, who portrays the brothel madam Meg Latimer, was an experienced Montreal stage actress, and The Pyx marked her feature film debut.

[5] According to Samuels, the Hollywood-based financiers of the project backed out two weeks before filming was to commence, after which the Royal Bank of Canada stepped in and offered to provide additional funding.

[35] Beatrice McKenna of Films in Review wrote: "Director Harvey Hart has worked well with editor Ron Wisman in using flashbacks and cutting, giving pace and excitement and a good deal of suspense to a plot which opens with the death of Karen Black...  Miss Black gives a fine performance, ably assisted by Christopher Plummer, a policeman investigating her death.

"[36] Edward L. Blank of The Pittsburgh Press praised Black's performance as her "best yet", also lauding the film's old-fashioned narrative style, but conceding: "Today's audiences, I fear, won't try something (for them) different.

"[37] Kevin Thomas of the Los Angeles Times praised the film, describing it as "bleak in atmosphere and hypnotic in effect... compelling entertainment that holds the viewer with mounting suspense while inviting him to contemplate the eternal struggle of good and evil, the paradoxical relationship of innocence and corruption and, finally, the nature of saintliness itself...

"[41] Jean Dietrich of The Courier Journal similarly felt that the film's editing style was choppy, rendering it at times "incomprehensibly dull...

"[42] Several critics drew comparisons between The Pyx and Alan J. Pakula's Klute (1972), another film that centers on a murder and involves a prostitute (portrayed by Jane Fonda): Douglas Beach of the Cedar Rapids, Iowa Gazette felt The Pyx was not as strong and that its screenplay "just doesn't give [Black] the room to match Miss Fonda's Oscar-winning effort.

"[43] Thomas of the Los Angeles Times similarly compared the film to Klute, citing its "incisive portrait of a prostitute," also drawing a comparison to Rosemary's Baby (1968) for its depiction of Satanism.

"[44] Michael Washburn of the National Review praised the film in 2020 as a "a haunting, eerie 1973 movie... starring the late Karen Black as Elizabeth, Christopher Plummer as a detective assigned to her case, the legendary Quebec stage actor Jean-Louis Roux as the devil-worshiper who organizes the deadly ritual, and, in perhaps its most interesting role, Terry Haig as Elizabeth's friend, a sensitive and sad young homosexual named Jimmy, who tries to help solve the murder only to meet a bloody end.

"[45] Assessing the film for Cult MTL, Alex Rose writes: "The Pyx mixes dime-novel pulp with headier themes in a not particularly successful way.

Plummer brings a giant dose of class to the film (not exactly surprising), but it remains stuck firmly between its grimy roots and its desire to be something a little more cerebral.

[47] Scorpion Releasing issued a remastered edition of the film on DVD on October 8, 2011, featuring an audio commentary with Black moderated by Marc Edward Heuck.

[1] The Academy's Margaret Herrick Library also holds numerous promotional materials, manuscripts, press kits, screenplay drafts, and associated items related to the film in their collection of Curtis Harrington's papers.