In the wake of a botched exorcism that ends in the deaths of a fellow priest and a pregnant woman, Father James [Tom McLaren] and Father John Barrow [Devon Sawa] are confined to a Catholic mental asylum. Chaplain Henry Davies [Peter MacNeill] informs Barrow that the Vatican has revoked his priestly status, setting a dark tone for the institution’s murky rituals and fractured trust. Meanwhile, Molly Hartley [Sarah Lind] is arrested after police discover the bodies of two friends she had been involved with the previous night. During intense interrogation, she hears strange noises, her voice shifts and deepens, and she begins to refer to herself as “we”—a phenomenon that unsettles everyone around her. She is sent to the same asylum for psychiatric evaluation, where Dr. Laurie Hawthorne [Gina Holden] witnesses her condition worsen as an insect-like creature appears to take up residence inside her.
As Dr. Hawthorne reviews Molly’s past, she uncovers a chilling claim Molly once made to her high school guidance counselor: that she was claimed by the devil on her eighteenth birthday, described as an incubation lasting six years, six months, and six days, a history that apparently involves Dr. Emerson and Molly’s ex-boyfriend Joseph Young, both of whom died in a double suicide after Molly left for Michigan. The mounting supernatural events surrounding Molly push Hawthorne toward the unsettling conclusion that possession is real, and she seeks a dangerous solution. She asks [Father John Barrow] to perform an exorcism in exchange for his release from the asylum; Barrow is initially hesitant, but after a coworker’s suicide, escalating disturbances, and seeing Molly herself up close, he is drawn into Davies’s world and agrees to help, donning clerical attire and gathering the ritual tools.
Barrow’s exorcism is harrowing and surgical: he forces the insect-demons to crawl from Molly’s mouth into a specially prepared box, sealing the container within a basin of holy water. He hands the box back to Davies, who stores it in his basement, a quiet repository that hides a growing threat. Barrow soon notices Davies’ Satanic tome, and Davies explains that the letters on the cover align with Molly’s forehead during the exorcism—revelations about Leviathan, the fourth book of the Satanic Bible that posits the Antichrist will be born after a supreme act of matricide tied to the “mother of the devil,” the person used to incubate the malevolent child. Barrow demands to see the box again, but Davies betrays him, replacing it with a heavy stone and knocking him unconscious.
When Barrow awakens, he finds himself in a locked room in the asylum. He witnesses a patient committing suicide in an adjacent chamber filled with the dead. An orderly leads him to an underground chamber where Davies participates in a ritual to sacrifice Molly to summon the Antichrist and, in a grim twist, to declare Barrow the father of the devil for extracting the demon. Before the ritual can be completed, Dr. Hawthorne lunges in and stabs Davies, interrupting the ceremony, dropping the box, and releasing the insects. Molly’s counterattack follows as she stabs Davies, and Barrow, Hawthorne, and Molly seize the chance to escape while the insect horde turns against the other ritual participants.
The trio makes a narrow escape, and Molly is rushed to safety in an ambulance, her future uncertain but her bond with Barrow and Hawthorne undeniable. Yet the story closes on a chilling note: one of the insects slips free and flees onto a moving school bus, creeping toward an isolated girl in the back seat as the screen fades to black, leaving the audience with a haunting sense of an evil that may not be finished.
