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.

On Halloween night, Kristen and David are sent to assess an exorcism; Ben goes on his favorite show, where he debunks supernatural finds with fellow unbeliever Vanessa.

When Kristen, David and Ben are asked to assess the veracity of a local prophetess, they are shaken when they see one of her visions come to life; David struggles with jealousy when he sees God speaking with the prophetess.