 Rosemary and Guy Woodhouse move into an apartment in a building with a bad reputation. They discover that their neighbours are a very friendly elderly couple named Roman and Minnie Castevet, and Guy begins to spend a lot of time with them. Strange things start to happen: a woman Rosemary meets in the washroom dies a mysterious death, Rosemary has strange dreams and hears strange noises and Guy becomes remote and distant. Then Rosemary falls pregnant and begins to suspect that her neighbours have special plans for her child.