Following his early retirement as a detective from the San Francisco Police Department, John Ferguson - Scottie to his friends - becomes obsessed with two women in succession, those obsessions which trouble his long time friend and former fiancée, Midge Wood, a designer of women's undergarments. The first is wealthy and elegant platinum blonde Madeleine Elster, the wife of his college acquaintance Gavin Elster, who hires John to follow her in Gavin's belief that she may be a danger to herself in thinking that she has recently been possessed by the spirit of Carlotta Valdes, Madeleine's great-grandmother who she knows nothing about, but who Gavin knows committed suicide in being mentally unbalanced when she was twenty-six, Madeleine's current age. The second is Judy Barton, who John spots on the street one day. Judy is a working class girl, but what makes John obsessed with her is that, despite her working class style and her brunette hair, she is the spitting image of Madeleine, into who he tries to transform Judy. The initial question that John has is if there is some connection between Madeleine and Judy. What happens between John and individually with Madeleine and Judy is affected by the reason John took that early retirement: a recent workplace incident that showed that he is acrophobic which leads to a severe case of vertigo whenever he looks down from tall heights.