The Exorcist is a propulsive psychological thriller following two very different priests tackling one family's case of horrifying demonic possession. Father Tomas Ortega is the new face of the Catholic Church: progressive, ambitious and compassionate. He runs a small, but loyal, parish in the suburbs of Chicago. He has no idea that his quiet life is about to change forever. Deep in the slums of Mexico City, another priest has found himself locked in a life-and-death struggle with evil. Father Marcus Keane is a modern-day Templar Knight, an orphan raised since childhood by the Vatican to wage war against its enemies. Father Marcus is everything Father Tomas is not: relentless, abrasive and utterly consumed by his mission - and he constantly butts heads with his adversary within the church, Father Bennett.
Caught in the middle of the two priests is the Rance family, who are members of Tomas' parish. On the surface, they're a normal, American family, but all is not as it seems in this household. The patriarch, Henry Rance, is recovering from a traumatic injury. Eldest daughter Katherine has become a recluse who refuses to leave her room. Her younger sister, Casey, thinks she's hearing strange noises coming from inside the walls. And mother Angela believes there is something in the house, a demonic presence, growing stronger by the day. Desperate, she begs Father Tomas for help, unwittingly setting the naïve young priest on a collision course with Father Marcus. Separately, each faces an insurmountable task, but together they become the Rances' only hope against an evil force that has been mobilizing for centuries.