Jim and Slim, two workers at a chemical plant in the New England town of Ravensback, decide to call it a day and head for the bar. A large buildup of pressure leaks from one of the pipes that starts to form a yellow toxic cloud that drifts across the ground. Meanwhile, a school bus is taking children home. After dropping one child off, five children are left on the bus.
After Gil Rogers as Sheriff Billy Hart finds the idling bus abandoned near a cemetery, he radios his deputy and dispatcher. Billy orders a roadblock at the intersection of the main highway and the lone road leading into town, recruiting a couple of armed locals, believing that the children were possibly kidnapped. The tension in the air grows as the lawmen prepare to act, driven by a mix of duty and unease about what might be really happening to the kids.
On the road, Janet Shore, Julie Carrier, stands in the middle of the road, dazed and pale, alongside others who seem equally stunned. They place her in the car to drive her home, and she appears to be only partially transformed at first. John Freemont, Martin Shakar, accompanies the sheriff, and the pair observe the disturbing change as Janet begins to lose herself to the creeping radiation-induced condition during the ride—her fingernails turning dark as the infection deepens. The car’s path becomes a tense chase as Janet lunges, and the officers manage to dodge her attack and retreat.
As the situation unfolds, Ellen Chandler, Sarah Albright, Tommy Button, Nathanael Albright, and Paul MacKenzie, Jeptha Evans, are spotted wandering together as zombie-like figures. They are eventually confronted, and the deputy on duty radios for help, only to be cut off mid-communication as he is killed. The trio of children then converges in front of the general store, where the dispatcher steps outside to greet them, only to be roasted to death in a horrifying, silent blaze that echoes over the police radio as John and Billy listen in with growing horror.
Billy fires at the zombified children, but his bullets have no effect on them. Cathy Freemont, Gale Garnett, unaware of the full extent of their condition, knocks Billy out with a glass object to prevent him from shooting the children. She then discovers Clarkie’s roasted body and calls out to John, who climbs upstairs, grieving, and lays the child to bed again. The emotional weight of the moment underscores how fragile the boundary is between ordinary life and the nightmare unfolding around them.
Paul attacks the adults, while Billy instinctively picks up a replica katana and chops off both of Paul’s hands as he howls in pain, a brutal moment that leaves the fingernails on the severed hands returning to normal. Ellen breaks through a window with one hand, only to have that hand immediately severed by Billy, signaling a grim turn toward the end for the most resilient of the undead kids. Billy and John then go outside with the sword in hand to find the remaining zombies, while Cathy watches and fears what further changes may come.
The three remaining zombies—Tommy, Janet, and Jenny Freemont—converge on the upper level of John’s barn, where the two men confront them. Despite Jenny’s pleas, the two men move decisively, dismembering and killing the trio in a brutal, premeditated defense of their home.
The next morning, Cathy yells to the still-sleeping John that “it’s time.” John rushes inside to help her deliver their third child. As the baby is born, the camera lingers on the deathly quiet from the night before, showing all five zombified children lying dead and still, with Sheriff Hart’s body among them but Clarkie’s not. After the birth, John stares in shock at his newborn, who has black fingernails while being breastfed by Cathy, a chilling subtle sign of the strange contamination that remains even in life.
