An emotionally fragile young woman has a love relationship with a married man. She thinks he intends to leave his wife, but as she gradually realizes that he is not, she begins to fall apart. She believes she sees her twin sister, who she was told had died as a baby. She sees the sister in the street and in the graveyard and the sister also sits in the bedroom and watches over her, when her lover is there. Her friend talks her into confronting her lover and demand that he commits himself. She arrives at his home at his wife's birthday party. He throws her out and her sister tries to lure her into drowning herself but leaves her alive at the last moment.