On a snowy December night, a state execution transfer vehicle crosses into the quiet backwater town of Snowmonton. Inside is serial killer Jack Frost (Scott MacDonald), who eluded police for years and left a trail of thirty-eight bodies across eleven states before finally being arrested by Sam Tiler (Christopher Allport), the sheriff of Snowmonton. Jack is scheduled to be executed at midnight, but Jack kills the guard and the vehicle crashes into a genetic research truck. Jack is exposed to chemicals from inside the truck, causing him to dissolve and fuse with the snow.
Despite news reports of Jack’s demise, Sam cannot forget Jack’s threats of vengeance. Old Man Harper is found murdered, and soon afterwards a local bully named Billy (Nathan Hague) is killed when he is pushed into the way of an oncoming sled, getting decapitated. According to Tiler’s son, Ryan (Zack Eginton) a snowman caused Billy’s death. Billy’s parents Jake (Jack Lindine) and Sally (Kelly Jean Peters) are then later murdered by the same snowman.
FBI Agents Manners (Stephen Mendel) and Stone arrive in Snowmonton and convince the Sheriff to put the town on 24-hour curfew, sending his officers out to gather all the townspeople. Deputy Chris Pullman (Brian Leckner) is killed when the snowman runs the officer over with a police cruiser. Billy’s older sister Jill (Shannon Elizabeth) and her boyfriend sneak into the sheriff’s home to steal his wine and have sex, as revenge for her family’s death. The snowman kills Jill’s boyfriend and pretends to be bath water to lure in Jill, solidifying around her and proceeding to rape and physically assault her, resulting in her death.
The snowman returns with the police cruiser to the station, finally confronting Sam. Agent Stone reveals himself to be a representative of the genetic research company that created the chemicals and reveals that the snowman is a mutated Jack Frost. He also reveals that the human soul exists as a chemical and that the acid was going to be used to contain DNA in case of a nuclear holocaust. They attempt to destroy Jack by blowing him up by releasing aerosol cans in the police station and firing a bullet at him, but to no avail. They then use blowdryers to drive Jack into a furnace, which evaporates the snowman. Jack condenses, killing Stone and wounding Manners. Jack traps Tiler and Ryan within his car, but Tiler escapes by inadvertently throwing the oatmeal Ryan made him at Jack, burning the snowman’s head. Ryan put antifreeze in the oatmeal, believing it could help keep his father from getting cold.
Sheriff Tiler tells his friend, Paul Davrow (F. William Parker) to fill the bed of his truck with antifreeze. Jack chases Sam through the halls of a church and finally catches him, driving an icicle into his chest and almost killing him. The truck full of antifreeze arrives just in time, however, and Jack and Sam crash through a window and into the truck’s bed. Jack Frost melts in the antifreeze, and the antifreeze is poured back into the containers, and buried deep under the ground of Snowmonton. Tiler’s wife Anne (Eileen Seeley), realizes that the state police are on their way. When Paul asks Tiler what they are going to tell them, Tiler says, “we’ll tell them that it’s too late”. However, one of the containers is shown to be bubbling, revealing Jack is still alive.