Cujo is a regular dog for the first part of the movie, but a bite from a vicious bat turns the once friendly Saint Bernard into a terrible beast that kills anyone and everyone who is daring enough to cross paths with him. Donna Trenton and her son, Tad, are going to Cujo's owner's house when their car breaks down. To make things worse, Cujo, who had already claimed two victims in the house, is lurking just outside the car, ready to attack them. He attempts to kill Donna and Tad continuously while they are stuck