Cujo, a friendly and easygoing St. Bernard (dog), chases a wild rabbit and inserts his head into a cave, where a Rabies bat bites his nose. Meanwhile, the Trenton family — advertising executive Vic (Daniel Hugh-Kelly), housewife Donna (Dee Wallace) and their sensitive young son Tad (Danny Pintauro) — take their car to the rural home of abusive mechanic Joe Camber (Ed Lauter) for some repairs, where they meet Cujo (the dog from the prologue), who is the Camber family's pet.