An aging widow, Claire Marrable (Geraldine Page), relocates to Tucson, Arizona after her husband's death leaves her in financial trouble. To continue thriving, she hires a succession of older ladies as companions at her desert home, each one disappearing mysteriously and eventually being murdered. As the new housekeeper, Mrs. Dimmock (Ruth Gordon), arrives with a reported $46,000, Claire's sinister intentions are revealed, leading to a dark confrontation that ultimately exposes her deadly secret.