After her parents separate, preteen Margot sets out to reunite her family. One day, she comes home from school to discover, to her shock, that a stranger has moved in and appears to have bewitched her father. Increasingly disturbed by the inexplicable phenomena surrounding this strange stepmother, Margot is convinced she is dealing with a real, evil witch. Determined to save her family, Margot calls on Mrs. Dalloway, a self-proclaimed occult expert, hoping she can help her get rid of the intruder who has taken her family hostage.