Cotton Marcus (PATRICK FABIAN) is a married preacher and husband in Baton Rouge who comes from a long line of men of God and, more uniquely, those who practice exorcisms. Yet, Cotton has lost his belief and wants to expose exorcisms and exorcists for the frauds he believes them to be. Accordingly, he's hired a video crew -- the never seen Daniel on camera and Iris (IRIS BAHR) handling the audio -- to follow him on such a case.
He randomly picks a letter asking for his help and gets one from Louis Sweetzer (LOUIS HERTHUM) of Ivanwood, LA, who states demonic things are taking place on his farm, mostly notably the nighttime slaughter of farm animals. Cotton and his crew arrive at the remote location and, after a less than friendly meeting with Louis' son, Caleb (CALEB JONES), who isn't happy they're there, discover that Nell (ASHLEY BELL) is reportedly the one suffering from demonic possession.
She's Louis' 16-year-old daughter who's been home-schooled by her highly religious father following his wife's death from cancer two years earlier. Cotton knows she isn't possessed, but realizes he can help her by making her think she is and that his exorcism will stop the possession. Accordingly, he fakes the entire thing, collects his fee, and then heads out.
But then Nell shows up at his motel room, miles away and without prior knowledge of his plans, and appears to be under a trance. Cotton and his team realize she needs psychological help, and thus accompany her back home from the hospital when Louis refuses to accept any outside help. From that point on, progressively odd, unsettling and then scary things start happening, all of which make Cotton reassess his opinion on possessions and exorcisms.