The film takes place in 1957, 13 years before the events of The Conjuring. The story follows a young nun named Sister Esther (Caroline O'Connor) and a group of orphaned girls, including Evelyn (Mira McNally) and Billie (Jocelyn Donahue), who live in a convent in Los Angeles. When the convent is shut down due to the nun's mysterious death, the girls are sent to live with a strict and abusive caretaker, Evelyn's aunt. As the girls try to cope with their new life, they begin to experience terrifying supernatural events.