Filmmakers Iris and Daniel follow Cotton Marcus, a reverend living in Baton Rouge, Louisiana, who seeks to delegitimize exorcisms. Marcus, who lost his faith after the birth of his ill son, is accustomed to performing fake exorcisms on "possessed" individuals. He accepts an exorcism request sent by farmer Louis Sweetzer, who claims his livestock are being slaughtered by his daughter Nell; Louis suspects that Nell is possessed by Satan.