On a snowy December night, a state execution transfer vehicle crosses into the quiet backwater town of Snomanton. Contained within the truck is serial killer Jack Frost (Scott MacDonald), who eluded police for five years and left a trail of thirty-eight bodies across five states before finally being arrested, ironically enough by the sheriff of the same town the truck had just entered. Frost is scheduled to be executed at midnight that night. However, due to the snowy weather, a tanker from the GCC that is driving the other direction collides with the prison truck, freeing Jack. As he tries to make his escape, the acid contained within the tanker breaks free, horribly scarring Jack. He falls to the ground, and his body begins to fuse with snow.
Meanwhile in Snowmanton, Sheriff Sam Tiler (Christopher Allport) continues to be haunted by the memory of Jack Frost. Despite news reports of Jack's demise, Sam cannot forget Jack's threats to get revenge on the sheriff, his family, and the whole town no matter what it takes. The sheriff's fears soon prove to be founded when Old Man Harper is found murdered, his head forced back as if by a giant mitten. Soon afterwards, a local boy named Billy (Nathan Hague) is also killed, decapitated by a sled after he "fell" into its path. According to the sheriff's son, the snowman pushed the boy in the way. Billy's parents are murdered, Jake (Jack Lindine) is having an axe shoved down his throat, Sally (Kelly Jean Peters) was being strung up like a Christmas tree.
Hearing of the murders, Agents Manners (Stephen Mendel) and Stone (Rob LaBelle) arrive in Snowmanton, claiming to be from the FBI. At the behest of the agents, Sheriff Tiler puts the town on 24 hour curfew and sends his officers out to gather all the townspeople. However, one of the officers (Brian Leckner) is killed when Jack Frost melts down and refreezes within his police cruiser, running the officer over. Two teens (the girl being Billy's older sister) are also killed when they sneak into the sheriff's house to be alone together and get back at him for the death of her brother. Tommy (Darren O. Campbell) dies when Jack drives an icicle through his head. Jill (played by Shannon Elizabeth) is killed when Jack reforms in the tub and moving his carrot nose to her crotch, trapping her arms in his shoulders and raping her. While she tries to break free, Jack then proceeds to beat her head against the wall until she is dead.
Jack Frost returns with the police cruiser to the station, finally confronting Sheriff Sam Tiler. The agents reveal themselves to be representatives of the genetic research company that created the acid and reveal that the snowman is a mutated Jack Frost. Stone also explains that the acid bounds a human chromosome helix so they can be resurrected in the future in case of a global holocaust, the snow not only stored Jack's DNA but his personality, and that his soul exists as a chemical. 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. Unfortunately, Jack condenses, killing Agent Stone and wounding Agent Manners. Jack Frost traps Sheriff Tiler and his son, Ryan (Zack Eginton) within his car, but the sheriff escapes by inadvertently throwing the oatmeal his son made him at Jack, burning the snowman's head. His son, not wanting his father to be cold, put antifreeze in the oatmeal, believing it could help keep the oatmeal from getting cold.
Sheriff Tiler tells his friend, Paul Davrow (F. William Parker) to fill the bed of his truck with antifreeze. In the movie's conclusion, Jack chases Sam through the halls of a church and finally catches him, driving an icicle into his chest and almost killing him. But the truck full of antifreeze arrives just in time, and Jack and Sam crash through a window and into the truck's bed. Jack Frost melts in the antifreeze, and the antifreeze is buried deep under the ground of Snowmanton. 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'. But in one of these containers shows it bubbling. It seems Jack's contained as a liquid, and is still alive.