Lesley, a troubled single woman in her thirties, lives in an isolated farm estate miles from the nearest town. Someone is committing murders in the vicinity, and the only suspects are Lesley or her brother Kevin. Among the victims are a hitchhiker looking for food, Susie, a local girl, Bobby, a young farmhand, and 'Twinkle', a middle-aged prostitute. Despite the attentions of compassionate Doctor Emerson, Leslie sinks further into depression and sexual frustration; her only source of happiness is her own brother, to whom she is attracted. But is Kevin real, or a figment of Lesley's imagination?