Just as audiences are forever haunted by The Exorcist, its director has spent 45 years plagued by a nagging uncertainty: as he'd never seen an exorcism, how could he be confident that he got his depiction right? And so it is that William Friedkin, still a showman and shift disturber of the highest order, hooks up with a 91-year-old Italian exorcist in hopes of committing the ritual to film. In turn, he delivers an investigation of evil that raises questions about whether filmmakers are really to be trusted.