Mike Kovak (Colin Odohono Colin O'Donoghue) is a seminary student from a funeral family, but he can't find any faith in his heart. By chance, Mike was sent to the Vatican to attend a training course for exorcists. He still had doubts about God, not to mention the mysterious exorcism ceremony, Mike debated with the teacher from a scientific point of view. On the recommendation of his teacher, he went to visit Father Lucas Trevor (played by Antonio Hopkins Anthony Hopkins), who is famous for his exorcism. Although he personally experienced the exorcism of Father Lucas, he still did not believe in the existence of the devil until a series of strange things happened to him, and the depths of Mike's soul was really shaken. Based on Matt Baglio's novel ritual: the manufacture of Modern Exorcists, the story is inspired by real events.