16-year-old Gracelyn Green has spent her entire life in the extreme and insular world of a religious cult. When the remote compound goes up in flames during an FBI raid, nearly all of her fellow cult members, including the charismatic leader and Grace's older sister, are killed. The few survivors, including Grace and her best friend, Sami, are dispersed to homes and facilities around the country. Grace is taken to New Jersey to live with an uncle and cousin she's never met. Brainwashed into hating all "disbelievers," Grace plots her escape, but her sessions with a skillful therapist reveal cracks in her rigid belief system, especially in regard to Sami, and she finds herself increasingly torn between her loyalty to her former "family" and the scary but life-affirming feelings that her new world has sparked.