The Unholy Wife

The Unholy Wife is an American 1957 color film noir drama film produced and directed by John Farrow at RKO Radio Pictures, but released by UniversalInternational as RKO was in the process of ceasing its film activities. The film features Diana Dors, Rod Steiger, Tom Tryon and Beulah Bondi. The screenplay was written by William Durkee and Jonathan Latimer

The film begins with Phyllis Diana Dors telling her story in flashbacks. It begins how she meets rich vintner Paul Hochen Rod Steiger from Napa Valley in a bar and marries him soon after.Not long after the marriage, Phyllis begins having an affair with a local rodeo rider, San Sanford Tom Tryon, seeing him every time her husband is away, which is frequently. One night, her elderly motherinlaw Beulah Bondi thinks a burglar is breaking into the house, so she calls the police. Phyllis sees this as an opportunity to kill her husband and blame the burglar for the crime. The plan backfires a day later when she instead kills her husbands best friend. Not wanting to go to jail, she convinces her husband to confess to the killing and they concoct a story that would set him free after the trial. ........

Source: Wikipedia