Erin Bennett, a high school senior, faces the possibility of missing out on the senior play because of the violent headaches that have afflicted her since her sister's death a year before in a car accident. No physical cause has been found for the headaches, and her parents have insisted that she see a psychotherapist. Erin goes, resentfully at first, and after a few weeks begins to accept the possibility that her continuing pain may have something to do with the stress of unresolved grief which is exacerbated by various trigger events.

She is cast in West Side Story opposite David, to whom she takes an instant dislike, though she has the haunting feeling she has seen him before. Attracted to her, he pursues her despite fairly direct rejection, until Erin figures out where she's seen him: she took her sister's place once in clown costume and makeup at a party where he was also a clown.

David, whose little sister is hearing impaired, helps bring Erin to a place of acknowledging the ways in which she is hanging on both to her grief and to unresolved anger at her sister's boyfriend. She also blames herself for the accident, since she asked her sister to take the car on an errand in her place.

At a final counseling session, the therapist helps Erin and her parents understand how, in focusing attention on Erin's headaches instead of their own unattended grief, they have become "stuck" in a loop of stress and alienation. Going through a trunk of her sister's things, Erin finds a way ritually to say good-bye and joins David at a party with a renewed willingness to choose life and a hope that she can free herself from both blame and pain.