Forensic psychologist Kristen Bouchard is hired by the Catholic Church to work with David Acosta, a priest-in-training, and contractor Ben Shakir, to determine whether a serial killer is possessed by a demon or merely a psychopath. Kristen finds that she has a taste for the work and is invited to join the team on a permanent basis.

After a high-strung theater producer's behavior turns from demanding to what is believed to be demonic, Kristen, David and Ben are called in to assess the situation. Also, Kristen discredits her DA office successor and nemesis, Leland Townsend, before he can ruin a 17-year-old boy's life.