Synopsis

A bizarre tale of sex and psychodrama begins when Cathy, an inexperienced young artist, is befriended by Ruth, a worldly and sophisticated woman. On the spur of the moment, Ruth invites Cathy to live with her. At first, Ruth is flattered by Cathy's devotion, and the undertones of a lesbian relationship bring them closer and closer. As Cathy develops a possessive fixation on the older girl, we begin to realize that she has a dark, psychotic side to her nature. At a house party given by Ruth, she encourages Cathy to mingle with her guests. Cathy is persuaded by Michael, a gentle, handsome man, to go with him to his home. There, in spite of herself, she succumbs to his masculine charm. It is her first love affair with a man and she is torn by her feelings toward Ruth and her newly found attraction to Michael. She confesses to Ruth these mixed emotions and of her affair with Michael. Ruth tries to explain to an innocent Cathy, that it is possible to love more than one person at the same time. Later, in a chance meeting, the triangle takes form. Ruth and Michael are attracted to each other and begin an exciting courtship. They try to let Cathy down gently but she is hurt and confused. In their desire not to hurt her, they include Cathy in all their activities, but soon their longing to be only with each other leads Ruth and Michael to exclude Cathy more and more from their company. Eventually in a desperate move to break away, Ruth and Michael go to Acapulco. Brooding alone, Cathy is torn between the two people she loves. In a scene remarkable for its outstanding photography, she fantasizes the murder of Ruth and Michael, her tortured mind rationalizing her act because she had loved them both. She has crossed the thin line between love and hate and now they must pay for her rejection. The is one of the most eerie and bizarre murder scenes ever put on film. As Cathy's fantasy comes to an end, we find Ruth and Michael at the door. They are returned from their vacation and together they inform Cathy that they were married in Acapulco. Cathy feigns delight, but starts living out her nightmare in reality. As the picture ends, suspense grips us and we are left wondering whether or not Cathy's murderous fantasy will become real.