La Iglesia Católica contrata a la psicóloga forense Kristen Bouchard para que determine si un asesino en serie está poseído por un demonio o es simplemente un psicópata.

Kristen, David y Ben investigan el supuesto milagro de la resurrección de una adolescente casi dos horas después de ser declarada muerta. Kristen se reúne/encuentra con su antiguo jefe y conoce a Leland Townsend.

Cuando el comportamiento de un productor de teatro muy nervioso pasa de ser exigente a lo que se considera demoníaco, Kristen, David y Ben deben evaluar la situación. Kristen desacredita a Leland Townsend, antes de que este le arruine la vida a un muchacho de 17 años.

El equipo es contratado para evaluar a un niño de 9 años que muestra (cierta) simpatía por David, lo que les da la esperanza de poder frenar su comportamiento violento. Kristen está preocupada por sus hijas, que mienten sobre un juego de terror que su abuela les ha comprado a sus espaldas.

David y Kristen no están de acuerdo con respecto a un exorcismo. Ben trata de desacreditar a los cazadores de fantasmas que salen en televisión. Las niñas juegan un juego peligroso con un psicótico compañero del colegio durante una fiesta de pijamas de Halloween.

When the Catholic Church asks Kristen, David and Ben to assess the veracity of a local prophetess, Grace Ling, they are shaken when they see one of her visions come to life.

When Bridget confesses to murder during her exorcism, Monsignor Korecki asks Kristen, David and Ben to investigate if the details match any open cases and if the woman really is possessed by a demon.

When David recognizes one of the sigils in the Poveglia Codex from his father Leon's artwork, he and Kristen journey to a remote art commune to investigate its meaning and how it's related to David's family.

David is shocked to learn he is being sued for inflicting severe psychological harm on Caroline Hopkins, after he assisted in her exorcism. The accusation leads him to question his future as a priest, especially once he develops a very close connection with his defense attorney, Renée Harris.

Kristen, David and Ben are called to investigate an insidiously addictive Christmas song that's spreading among an increasing number of students, and the dangerous relationship between online influencers and their impressionable young followers.

After David is badly wounded, he is determined to fight off the menacing presence of death from his hospital bed.

Leland assists convicted serial killer Orson Leroux with having his conviction overturned; Kristen is called into court to testify while her daughter, Laura, undergoes emergency heart surgery; David witnesses a woman's evil instincts firsthand.

David, Kristen and Ben assess whether a pregnant woman is possessed when she claims one of the twins she’s carrying is evil. Their investigation leads to a fertility clinic where they discover a connection to all of their encounters throughout the season. Also, Kristen questions one of her daughters’ capacity for evil upon realizing that she also used that fertility clinic.