The Dark Recesses of the Female Mind. Irving Rapper’s Another Man's Poison is based on Leslie Sands' play "Deadlock," with a screenplay adaptation by Val Guest. The film features Bette Davis, Gary Merrill, Emlyn Williams, Anthony Steel and Barbara Murray, alongside music from John Greenwood and Paul Sawtell, and cinematography by Robert Krasker. It’s an enjoyable experience if you go in knowing what to expect. Another Man's Poison feels very much like a play brought to the screen, largely taking place in one location with attention centered on just five people and a horse. The story involves murder, lies, and sexual attraction, particularly Janet Frobisher’s (Davis) affair with a younger man who is also desired by her secretary. Frobisher is undeniably unpleasant, and Davis portrays her with gusto and a certain theatrical flair. She drives the narrative forward, but the other main characters aren't exactly bright; they are either foolish, unaware of what’s happening around them, scheming, or some combination of all three! It’s definitely a gathering of people you wouldn’t want to spend much time with. It's these characterizations, combined with Krasker’s visuals, that almost justify the film noir label. The writing isn't particularly strong – rumors about changes made by Williams and reports that Davis and Merrill (who were married at the time) had marital issues are widespread - but it doesn't drag on or become tedious, and seeing Bette being outrageous is always entertaining. 6.5/10

Source on TMDB