From The Art and Popular Culture Encyclopedia
Marion Post (Gena Rowlands) is a 50 year old philosophy professor. She is married to Ken (Ian Holm). She sublets a flat downtown so she can have peace and quiet while writing a philosophy book. However, through a vent, Marion can hear all the private revelations of the clients in a neighboring psychiatrist's office. Marion becomes particularly fascinated by one client (Mia Farrow) who is deeply depressed. Over the course of the film, her fascination with Hope forces her to examine her own life. She comes to realise that, like her father (John Houseman), she has been unkind and judgmental to various characters throughout her life: her dejected brother Paul (Harris Yulin) and his fragile wife Lynn (Frances Conroy), her best friend from high school Claire (Sandy Dennis), her first husband Sam (Philip Bosco), and her stepdaughter Laura (Martha Plimpton). She also realises that her current marriage to Ken is unfulfiling and that she missed her one chance at love with Larry (Gene Hackman). By the end of the film, Marion resolves to change for the better.