Marty (Demi Moore) is a single, high-powered literary agent in Manhattan. Marie is a widow who lives a peaceful life in Provence, France with her two daughters. When Marie falls asleep she dreams that she is Marty (Demi Moore) and when Marty falls asleep she dreams that she is Marie. Marty has been seeing a therapist to deal with her vivid dreams of Marie's life. Marie also sees a therapist, and confides in her older friend, Jessie (Sinéad Cusack), but she is much less disturbed by the dream life. Each woman is convinced that the other is a figment of her imagination. Marty's New York psychiatrist, Dr. Peters (Peter Riegert), feels that she is lonely in her busy life and wants to live a simple life with children to love. Marie's French psychiatrist, Dr. Langer (Joss Ackland), feels that she wants more than a drab home life and longs to lead a more exciting one. Through a business deal, Marty meets Aaron (William Fichtner), an accountant. They become friends and eventually lovers. Terrified that her vivid other life means that she's losing her mind, Marty doesn't want to tell Aaron about it but finally does. Marie, meanwhile, has met and fallen in love with William (Stellan Skarsgård), a writer. She too is reluctant to tell William about her dreams, particularly because she (as Marty) is falling in love with Aaron, but realizes that she cannot keep such an important part of her life a secret. The two men react very differently: William is jealous, and Aaron is skeptical but not at all threatened, and wants only for Marty to be happy. Dreams and reality begin to merge when Marie goes on holiday with William to Paris, and Marty wakes up with an ashtray from the hotel on her night stand. Eventually Marty/Marie must come to terms with reality and choose which life is real and which is illusion. Along the way, Marty and Marie find clues from each other's lives in each world. Yet, the real, tangible things are always found in the New York world. Eventually, she realizes that her New York Life is real and her French life is a dream. Marie's two daughters are herself when she was 7 and 11. Her friend, Jessie, is her memory of her mother who died when she was eleven. Marty gives Aaron her journals as a way to understand her better.