When Monty, the manager at All-Mart is preparing to open the store for Black Friday sales, he discovers a mysterious parasite which promptly attacks him turning him into a ravenous monster. He later attacks two employees also turning them into monsters and eventually causing the original infection to begin spreading through the town since all who get touched by the monsters turn into monsters themselves. The workers of the store and citizens of the town are soon left to fend for themselves against the monsters.