Cujo, a horror-thriller novel first published in 1981, is the 10th novel by the American “King of Horror,” Stephen King. It was inspired by a trip the author took to a mechanic in rural Maine whose St. Bernard nearly attacked King. Cujo received several accolades upon its release and won the British Fantasy Award for Best Novel in 1982. It was adapted into a film of the same name in 1983.

The citations in this study guide correspond to the 1982 Signet edition.

Content Warning: Note that this novel depicts explicit acts of violence and refers to death by suicide.

Plot Summary

Cujo takes place in Castle Rock, Maine during the summer of 1980. It’s an especially hot summer, one that the town’s oldest resident, Aunt Evvie, prophesizes will be evil and deadly. Aunt Evvie’s concerns scare young Tad Trenton, who continually wakes up in fright to a growling monster hiding in his closet. Though his parents, Donna and Vic, assure him that the monster isn’t real, Tad is unconvinced.

One day in June, a giant, kindly St. Bernard named Cujo chases a rabbit into a hole and gets stuck. He awakens a swarm of bats, which attack him and scratch his snout. Cujo runs away in panic, having unwittingly contracted rabies.

Cujo’s owner is Joe Camber, who runs Castle Rock’s auto repair shop. Joe’s wife, Charity, recently won the lottery, and she gets up the nerve to ask her abusive husband for permission to take their son, Brett, to Connecticut to visit family. Once Joe learns about Charity’s money, he allows her and Brett to go on the trip. Joe tells his friend, Gary Pervier, about Charity’s trip and his own plans to visit Boston while she’s away. As Joe jokes with Gary, Cujo silently grows sicker.

Meanwhile, Vic Trenton is planning a work trip with his business partner, Roger. The two men run an advertising firm out of Maine, having recently moved to the state from New York. Their largest client, Sharp Cereals, released a faulty batch of product that has caused minor health problems nationwide. Vic and Roger fear that their ad agency could close for good if they lose the Sharp account and want to travel to meet their client and brainstorm solutions.

Vic’s wife, Donna, has not adapted well to the move to Castle Rock. She cheated on Vic with a local artist named Steve Kemp but breaks it off before Vic leaves on his trip. A disgruntled Kemp, however, sends her husband a letter with intimate details about Donna to reveal that they had an affair. Kemp then leaves Maine, gleeful that he has likely destroyed Donna’s marriage. Vic and Donna argue about the affair a few nights before Vic leaves on his trip. He still plans to take the trip and promises Donna that while he’s away he’ll decide whether he’ll stay with her.

Just before he leaves, Vic advises Donna to take her car to Joe Camber’s yard to get it fixed before it breaks down for good. Vic has fond memories of the Camber yard; Joe fixed his car well, and Tad had fun playing with the sweet and gentle Cujo all afternoon.

The morning that Brett and Charity plan to leave for Connecticut, Brett finds Cujo disheveled and ill. Afraid that his father will force Brett and Charity to cancel their trip, Brett decides not to tell him about Cujo’s illness. Charity promises Brett that they can call Joe from Connecticut to check in.

That morning, Gary Pervier is in his garden when he hears growling. He turns to find Cujo. Gary runs toward his house, recognizing that Cujo’s appearance and attitude indicate rabies, but is unable to escape: Cujo bears down on him and rips his throat out, leaving a brutal murder scene.

As Charity and Brett travel to Connecticut, Joe goes to visit Gary before leaving for Boston. He finds his friend’s body and the bloody scene left behind. While Joe looks at Gary in horror, Cujo sneaks up behind him and kills him.

Donna’s car acts up that afternoon as she and Tad go grocery shopping; after calling Vic in Boston, she decides to take it down to the Camber yard for repair. Tad insists on going with her.

In Connecticut, Charity’s sister, Holly, and her children greet Charity and Brett. Brett is cautious toward Holly and her husband, Joe, thinking that they’re too prideful and flaunt their wealth. Charity urges Brett not to be too judgmental, as one of her goals for this trip is to ensure that her son hasn’t internalized her husband’s harmful, prejudiced ideas.

Donna drives with Tad to the Camber residence. On the way, the car acts up, and the engine dies as Donna reaches the Camber yard. She gets out, expecting to find Joe, but observes only eerie silence on the property. She suddenly hears a bone-chilling growl. Cujo emerges from the garage. Donna races back to the car and leaps in just before Cujo can reach her. He terrorizes Donna and Tad from outside the car, which won’t restart. As Donna stares at Cujo’s monstrous form, she realizes that she and her son are trapped, with no escape.

Brainstorming escape ideas, Donna realizes with relief that the mail should be coming the next morning. She falls asleep peacefully with the hope that rescue will arrive soon. However, the mail never comes, as the Cambers put a vacation hold on their delivery a few days earlier.

That day, Steve Kemp returns to Maine so that he can witness the fallout of his destructive letter firsthand. He stops by the Trenton place and ransacks the house, leaving a cruel, teasing note on the refrigerator for Donna.

At the Camber yard, Cujo is terrorizing Donna and Tad by ramming into the car. Shocked that the dog can survive the brutal trauma to his skull, Donna is convinced that a supernatural force—perhaps fate itself—is driving the animal. That evening, all goes quiet. Donna thinks Cujo is asleep and tries to run to the porch. Cujo springs on her, biting into her stomach and thigh before Donna closes the car door. She realizes she’s doomed, having been bitten by a rabid animal.

In Boston, Vic has a bad dream about Tad and Donna and suspects they’re in danger. When he can’t reach them by phone, Roger urges Vic to call the police. The Castle Rock Sheriff’s Department deploys officers to check the home and discovers the destruction that Kemp left behind. The Sheriff considers Donna missing and tells Vic to return to Maine. When Vic arrives, he and the Sheriff’s Department try to determine Tad and Donna’s whereabouts. They theorize that Kemp could have kidnapped them, but Donna’s missing car doesn’t fit this theory. When Vic tells the police about Donna’s car trouble, Andy Masen, a lawyer in the Maine Attorney General’s office, suggests sending an officer to Joe Camber’s property to investigate.

At the Camber yard, Tad is in bad shape and has heat stroke convulsions. Donna knows they have little time before they both die. When an officer arrives to investigate the Camber yard, Cujo attacks and kills him. Donna realizes she’s the only one who can act against Cujo. Wielding a baseball bat she finds in the yard, Donna attacks Cujo. After a bloody duel, she kills the dog by driving the splintered bat through his eye and into his brain.

Vic is convinced Donna must be at the Cambers. When the police officer never returns from the Camber property, Vic goes there himself and arrives to find Donna beating Cujo’s dead body with a baseball bat. Vic calms her down and asks where Tad is. He discovers his son dead in the car. The ambulance arrives to take Donna to the hospital and pick up Tad’s body. The Castle Rock Sheriff’s Department calls Charity at her sister’s house and notifies her of Joe’s death and Cujo’s chain of destruction.

When Donna returns home, she’s wracked with guilt over being unable to save Tad. She and Vic resolve to stay together.

Months after the incident, Charity and Brett resolve to remain on their old property together by living on a shoestring budget. They adopt a mongrel puppy and name him Willie.

Cujo’s body is beheaded, and the head is tested in the state lab for rabies. The result is positive, and the remains are cremated. The story closes by describing the cave where Cujo first contracted rabies. The bats have left, and the rabbit Cujo was chasing has died of starvation.