In New York City, Tom, an actor cast as a priest in a supernatural horror film titled The Georgetown Project (similar to The Exorcist), is mysteriously killed by a supernatural force while inspecting the set alone. The film’s demanding director, Peter, then selects aging and alcoholic actor Anthony Miller to replace Tom. Anthony’s daughter Lee, who has been suspended from high school, works as his personal assistant on the film. As Anthony’s history as a sexual abuse victim emerges, he struggles both on and off the set, frequently experiencing flashbacks of his trauma. Lee grows increasingly concerned about her father’s erratic behavior, which includes self-harm, sleepwalking, and refusing to take his medication.

Meanwhile, Lee befriends Blake, a popular TV actress who plays a possessed girl in the film. Together, they seek advice from Father Conor, a Catholic priest and psychiatrist consulting on the film, about Anthony’s disturbing behavior. On set, Anthony behaves as if he is possessed, contorting his body and slamming his head into a table. Later, when alone on set, Joe, the co-star who replaced Anthony, is killed by flying glass from a mirror after seeing a phantom of Anthony. At home, Anthony suddenly attacks Lee and then jumps out of a window.

Determined to stop the possession, Father Conor decides to perform an exorcism on set. Lee finds Conor and Blake paralyzed in front of the now-possessed Anthony, who mocks Lee’s attempts to use a prayer book. When Conor becomes possessed, Anthony is roused to stab him with a crucifix, using the prayer book’s exorcism rite sincerely with Lee’s help. Conor catches fire, and the demon is ultimately defeated.

In the aftermath, Anthony reflects on how his relationship with his daughter has improved. Lee soon begins working on a film script, signaling a new chapter in their lives.