The story is based on a real murder case that shocked the United States in 1981. After killing the landlord, the murderer Arne Cheyenne Johnson claimed that he was possessed by an evil spirit. This was the first case in American history where the defendant used "possession" as a defense, so it was called the "Demon Murder Case". 11-year-old boy David was possessed by an evil spirit and fell into a state of chaos. He often saw monster demons sitting on his favorite rocking chair, and strange scars appeared on his body... The frightened and helpless family invited the Warrens to intervene in the investigation. They found that David was possessed by 43 demons, which made him behave abnormally, such as crawling on the ground like a beast, talking nonsense, and even reciting the Bible and "Paradise Lost" chapters that he had not read... The Warrens then arranged for a priest to exorcise David, but unfortunately there was no improvement, and even more bizarre things happened one after another. David's sister's fiancé Arne also began to behave abnormally. A few months later, Arne stabbed the landlord to death with a sharp knife. The Warrens believed that Yarne was possessed by an evil spirit when he committed the crime. It turned out that Yarne was also present when David performed the exorcism...