Successful mystery novelist Janet Frobisher, who has been separated for years from her husband, a man with a criminal past, lives in an isolated home in Northern England. Her nearest neighbour is nosy veterinarian Dr Henderson. Janet has an affair with, and falls in love with, her secretary Chris' fiancé, Larry, who is years younger than she. When her estranged husband unexpectedly appears, Janet poisons him by administering medication given to her by Dr Henderson for her horse. One of the deceased man's criminal cohorts arrives as she's preparing to dispose of the body in the local lake. When Frobisher's secretary and Larry arrive at the secluded house, the mysterious man, who has assisted her with her scheme, impersonates George, the long-absent spouse of Janet. George and Janet trade accusations and insults. Chris learns of Larry's affair with Janet, and determines to leave for London. Janet tries to convince Larry to stay with her, but he loves Chris and chases after her unsuccessfully. George shoots Janet's horse to upset her. Janet pretends she is remorseful about Larry and Chris, and sends George after Chris in an unsafe vehicle. He crashes, but survives. The next morning the authorities are dragging the lake because of the crash. Janet's attempt to kill George has trapped them both, although George plans simply to run away. Janet tricks George into poisoning himself. As George dies, Dr Henderson arrives and says he knew all along that George was an imposter; the real George stopped by his house in the fogthe night he arrived. Janet pretends to faint. Dr Henderson gives her a drink from the same flask she used to trick George. When she opens her eyes and recognises the flask, she realises she has killed herself, and bursts into hysterical laughter.
Production notes
Of the project, star Bette Davis recalled "We had nothing but script trouble. Gary and I often wondered why we agreed to make this film after we got started working on it. Emlyn rewrote many scenes for us, which gave it some plausibility, but we never cured the basic ills of the story." This was the second on-screen pairing of then-married couple Davis and Gary Merrill, following All About Eve the previous year. They made Phone Call from a Stranger the following year. Rapper, who was selected by Davis to helm the film, had directed her in Now, Voyager ten years earlier. Co-star and script doctor Emlyn Williams wrote the original play on which Davis' 1945 film The Corn Is Green was based. Exteriors of the United Artists release were filmed on location in Malham, West Riding of Yorkshire, and interiors were shot at the Nettlefold Studios in Walton-on-Thames, Surrey.
The New York Times described the film as "a garrulous but occasionally interesting excursion into murder and unrequited love...the script...is basically a static affair that rarely escapes from its sets or the scenarist's verbosity. Suspense is only fitfully generated and then quickly dissipated...Gary Merrill contributes a thoroughly seasoned and convincing portrayal...Emlyn Williams adds a professionally polished characterization...and Anthony Steel and Barbara Murray are adequate...However, Another Man's Poison is strictly Bette Davis' meat. She is permitted a wide latitude of histrionics in delineating the designing neurotic who is as flinty a killer as any we've seen in the recent past." In his review in New Statesman and Nation, Frank Hauser wrote "No one has ever accused Bette Davis of failing to rise to a good script; what this film shows is how far she can go to meet a bad one."
