During World War II, Marine Willard Russell discovers Gunnery Sergeant Miller Jones brutally skinned and crucified by the Japanese. In a merciful act, Willard ends Jones’ suffering with a gunshot to the head. After the war, en route to his hometown of Coal Creek, West Virginia, Willard stops in Meade, Ohio, where he meets Charlotte, a diner waitress. They marry and settle in Knockemstiff, Ohio, where they welcome a son named Arvin.
Fast forward to 1950, Helen Hatton ties the knot with the eccentric yet captivating preacher Roy Laferty, who showcases his faith by pouring venomous spiders over his head during a sermon. Helen gives birth to Lenora, and soon after, Roy's reality begins to unravel due to a severe allergic reaction to a spider bite. In a delusional belief that he can bring the dead back to life, Roy tragically stabs Helen. When he realizes that she does not revive, he flees, desperate to see his daughter.
Roy's escape leads him to a fatal encounter with the serial-killing couple, Carl Henderson and Sandy. Their twisted modus operandi involves picking up male hitchhikers, seducing them, and then murdering them. When Roy declines to engage with Sandy, Carl has no hesitation in taking his life.
In 1957, as Charlotte battles cancer, Willard engages in fervent prayers, convinced that his devotion can sway God to heal her. In a desperate spiritual sacrifice, he kneels before a cross he erected in the woods and offers the family's dog. Despite his pleas, Charlotte ultimately succumbs to her illness, leading Willard to take his own life out of grief. Orphaned, Arvin is sent to live with his grandmother Emma and soon encounters Lenora, now his stepsister.
Seizing the 1965 scene, Arvin receives his father's Luger pistol as a birthday gift. The local church welcomes a new preacher, Reverend Preston Teagarden, whose extreme behavior raises concerns. After witnessing Lenora's torment by bullies at school, Arvin retaliates violently. Meanwhile, Teagarden exploits Lenora's vulnerability, leading to a harrowing encounter that results in her pregnancy. Unable to cope with the shame, Lenora contemplates suicide and tragically dies in the process.
Heartbroken, Arvin learns of Lenora's pregnancy and immediately suspects Teagarden’s involvement. He resolves to confront him and ultimately kills him with the Luger. In a turn of fate, Arvin finds himself hitchhiking again, only to be picked up by Carl and Sandy. Defending himself against Carl’s lethal intentions, Arvin kills both Carl and Sandy. Inside the glove compartment, he discovers a stash of photographs taken during their monstrous rituals.
With the local sheriff, Lee Bodecker, now aware of Sandy's murder, he seeks to dispose of the evidence. However, the tension escalates when Arvin returns to his childhood home. Their paths cross in the woods where the tragic events unravel, leading to a deadly exchange between Arvin and Lee. As Lee lies wounded, Arvin leaves behind incriminating evidence before catching a ride with a hippie in a VW van.
The story culminates with Arvin reflecting on his future, wondering whether he will become a devoted husband or a soldier in the Vietnam War, as the film concludes with a poignant sense of uncertainty and possibilities.
