Rosemary Woodhouse is a young woman who moves into a new apartment building with her husband, Guy. She soon becomes pregnant, but begins to experience strange and disturbing events. She suspects that her neighbors, the Castevets, are involved in a satanic cult and that they plan to use her baby for their own evil purposes. As Rosemary's pregnancy progresses, she becomes increasingly isolated and paranoid, and her grip on reality begins to slip. The movie culminates in a terrifying climax as Rosemary gives birth to her baby and discovers the truth about her husband and neighbors.