Mariel and Tino, a documentary filmmaking duo specializing in disturbing crimes, investigate a tragedy that occurred a year earlier at a care home, where a young volunteer named Gisela set fire to a dormitory with several children inside. Their investigation leads them to Father Román, a Vatican-sanctioned exorcist who claims to have treated her for demonic possession. Mariel refuses to believe him—until they discover a young woman locked in a forest cabin who claims to be Gisela and accuses the priest of holding her captive.