Rosemary Woodhouse and her struggling actor-husband Guy move into the Bramford, an old New York City apartment building with an onimous reputation and only elderly residents. Neighbours Roman and Minnie Castavet soon come nosing around to welcome them and, despite Rosemary's reservations about their eccentricity and the weird noises she keeps hearing, her husband starts spending time with them. Shortly after Guy lands a plum Broadway role, Rosemary becomes pregnant and the Castavets start taking a special interest in her welfare.

As the sickened Rosemary becomes increasingly isolated, she begins to suspect that the Castavet's circle is not what it seems.