Seventeen-year-old Millie Kessler spends her days trying to survive high school and the cruel actions of the popular crowd. But when she becomes the latest target of the Butcher, the town's infamous serial killer, her senior year becomes the least of her worries. When the Butcher's mystical dagger causes him and Millie to magically switch bodies, the frightened teen learns she has just 24 hours to get her identity back before she looks like a middle-aged maniac forever.