New York high-school student Lisa Cohen (Anna Paquin) inadvertently causes an accident in which a bus driver (Mark Ruffalo) runs over a pedestrian (Allison Janney). Guilt-stricken over her role in the woman's death, Lisa's mood swings from normal to furious, with her angry outbursts mostly directed at her mother (J. Smith-Cameron). Lisa reaches out to the dead woman's best friend (Jeannie Berlin) and the bus driver, but her failed efforts to make amends only lead to more hostility.