While traveling through the picturesque backroads of rural Mississippi after their honeymoon, Eli McCreary (Ronny Cox) and Caroline McCreary (Bibi Besch) find themselves in a harrowing situation when they miss a turn and their car becomes stuck in the mud. Seeking assistance, Eli sets off on foot to a nearby service station. Unfortunately, as he is gone, a mysterious creature attacks, resulting in the tragic loss of their dog and a horrific assault on Caroline, which leads to her becoming pregnant.
Fast forward seventeen years, their son Michael (Paul Clemens) is plagued by a disturbing illness that leaves him resembling a shadow of his former self, on the brink of death. After leaving him in the hospital, Eli and Caroline make the decision to return to Naiobi, Mississippi, the very town near where Caroline's ordeal occurred. They believe that understanding Michael's condition hinges on uncovering the identity of his biological father. Their investigation raises the suspicions of local magistrate Judge Curwin (Don Gordon) and the town's newspaper editor, Edwin Curwin (Logan Ramsey), who are wary of the dark history surrounding a horrific murder that coincided with Caroline's assault.
The narrative takes a darker turn as Michael, plagued by visions of locking something malevolent away in a cellar, escapes from the hospital. He impulsively steals a car and drives back to Naiobi, where fate leads him to Edwin Curwin's home. Mistaken for a grocery delivery boy, Michael gains entry, but in a shocking twist, succumbs to violent impulses, killing and partially consuming Curwin. Disoriented, he is later discovered by Amanda Platt (Katherine Moffat), who, concerned for his well-being, brings him to a local doctor's office. Dr. Schoonmaker (R.G. Armstrong) reaches out to Eli and Caroline, but everyone is taken aback by Michael's unexpected improvement in health.
As Michael's relationship with Amanda blossoms, they share a tender moment in the woods. However, their romance is interrupted when Amanda's dog unearths a human hand, prompting Sheriff Pool (L.Q. Jones), Judge Curwin, and Eli to begin a grisly excavation. Amanda's father, Horace (John Dennis Johnston), intervenes, forbidding her from seeing Michael, escalating the tension.
In a frenzied turn of events, Michael's actions become increasingly violent, including the murder of a relative of the Curwins and a confrontation with town drunk Tom Laws (Ron Soble). When revelations about Michael not being Eli's biological son surface, chaos ensues—Michael's struggle for identity intensifies.
Sheriff Pool and Eli's investigation leads them to a grotesque discovery: a deformed skeleton shackled in the cellar. In a climactic scene at the hospital, Michael undergoes a terrifying transformation in front of Dr. Schoonmaker, Caroline, Horace, and Judge Curwin, revealing the horrific truth behind his existence. After surviving multiple gunshots, Michael launches an assault on the county jail, resulting in Judge Curwin's decapitation.
Ultimately, Michael's horrific journey culminates in a tragic confrontation in the woods—echoing the very location of Caroline's assault—where he violently assaults Amanda. In an inevitable retaliation, Eli and Caroline along with Sheriff Pool arrive, leading to a desperate decision where Caroline shoots Michael in the head. The aftermath leaves all parties, including Schoonmaker, Caroline, Eli, and Sheriff Pool, standing silently, grappling with the unsettling reality of the night's grim events.
