Mystery writer Janet Frobisher lives alone in a dark English country house, when she's not philandering with her secretary's fiancée. At an extremely awkward moment, she has an unwelcome visitor George Bates, who claims to be the partner in crime of Janet's estranged husband. George insinuates himself into Janet's home and life despite her efforts to get rid of him; the tangled relationships develop into a macabre, murderous cat-and-mouse game.