The story follows Joan Mitchell, a 39-year-old woman in suburban Pittsburgh. Her husband Jack is successful, often away on business and controlling, and the marriage turns abusive. Joan is bored and unhappy with the role of obedient housewife, and she is having nightmares about being dominated.
She tries therapy first. Then she hears about a new neighbor rumored to practice witchcraft, goes over for a tarot reading with a friend, and starts reading up on spells herself. Each step pulls her further from the life everyone expects her to keep living.
The witchcraft is almost beside the point. Romero said at the time that the film was not really a horror movie and that it touches the occult only around the edges. He also called it a feminist film. The supernatural works as a way for Joan to imagine power she does not have at home, and the closing scene lands that idea with a dry, quiet sting.