Cujo is a two-hundred-pound Saint Bernard, the belved family pet of Joe Chambers of Castle Rock, Maine, and the best friend ten-year-old Brett Chambers has ever had. One day Cujo pursues a rabbit into a bolt-hole - a cave inhabited by some very sick bats. Vic Trenton, New York adman obsessed by the struggle to hang on to his one big account, his restive and not entirely faithful wife, Donna and their four-year-old son Tad, moved to Castle Rock seeking the peace of rural Maine. But life in this small town - evoked as vividly as Winesburg od a Spoon RIver - is not what it seems. As Tad tries to bravely fend off the terror that comes to him at night from his bedroom cloest and as Vic and Donna face their own nightmare of a marriage suddenly on the rocks, there is no way they can know that a monster, infinitely sinister waits in the daylight, and the fateful currents of their lives will eddy closer and faster to the horrifying vortex that is Cujo. - Book Flap

The Cambers' once-friendly St. Bernard turns into a killer after being bitten by a rabid bat. Donna Trenton's husband is in New York trying to contain a disastrous ad campaign. Feeling abandoned by her workaholic husband, who is frequently out of town, Donna Trenton embarks on an affair with a local handyman. Left to fend for herself, she takes her ailing Pinto to Joe Cambers' garage for repairs only to be trapped with her son Tad in the sweltering car by the monstrous dog. - Author website.