Mr. Mercedes

by Stephen King

Many jobless people are standing in line for a job fair, but then a Mercedes plows into the crowd, killing eight and severely injuring many. Bill Hodges, a recently retired detective from the local police department living the life of a retiree, receives a letter from an individual claiming to be the person responsible for the job fair incident, referring to himself as "Mr. Mercedes". Hodges is divorced, lonely, and fed up with his life, occasionally considering suicide. The incident had taken place at the end of Hodges' career and was still unresolved when he retired. Mr. Mercedes knows details of the murder and also mentions Olivia Trelawney, from whom he had stolen the Mercedes. Olivia had committed suicide soon after the massacre out of guilt. Hodges is intrigued and starts to investigate the case instead of turning the letter over to his former police colleague, Pete Huntley.

Brady Hartsfield, who is revealed to be Mr. Mercedes, is an emotionally disturbed psychopath in his late twenties who lost his father at age eight. When he was a young boy, he killed his mentally handicapped brother at his mother's prompting. He now lives with and has an incestuous relationship with his alcoholic mother and works in an electronics shop and as an ice-cream seller. Riding in a van, this second job enables him to observe Hodges and Hodges' neighbors, among them seventeen-year-old Jerome Robinson, who does small chores for Hodges.

During his research about the wealthy Olivia Trelawney, Hodges meets her sister Janey, who hires him to investigate Olivia's suicide and the theft of the Mercedes. Shortly after Hodges begins to work for Janey, the two begin dating. Hodges finds out, with the help of bright, computer savvy Jerome, how Mr. Mercedes stole the car and then drove Olivia (whom he made contact with through his job at the electronics shop) to suicide by leaving eerie sound files on her computer that were set to go off at unpredictable intervals, which escalated her feelings of guilt. Olivia, when hearing these sounds, believed them to be the ghosts of the victims of the Mercedes Massacre. At the funeral of Janey and Olivia's recently deceased mother, Hodges meets Janey's unpleasant relatives, among them Janey's emotionally unstable cousin Holly. After the funeral, Mr. Mercedes blows up Hodges' car, not realizing that Hodges wasn't in it. However, Janey was, and she is killed in the explosion. Hodges feels remorse but becomes even more eager to solve the case without the help of the police. Holly joins Hodges and Jerome in the investigation.

Hartsfield accidentally kills his mother with a poisoned hamburger, which he had prepared for Jerome's dog. With her rotting body in their house, he plans to kill himself by blowing himself up at a giant concert for young girls by feigning the need for a wheelchair and utilizing explosives hidden inside the wheelchair. Jerome, Hodges, and Holly manage to uncover Hartsfield's real identity and search his computer hard drives. They eventually deduce that Hartsfield's target is the concert, and the trio rush to the concert venue to stop him. Hodges begins to suffer a heart attack and is unable to venture into the concert with Holly and Jerome, but urges them to press on. Holly locates Hartsfield and delivers several harsh blows to his head using Hodges's "Happy Slapper" – a sock filled with ball bearings. Hartsfield is left bleeding and unconscious on the concert floor.

Hodges (who had been saved by concert staff), Holly, and Jerome have a picnic to discuss the recently transpired events. Hodges has learned that he will not be criminally charged for his actions regarding the Hartsfield investigation. They have received medals from the city, congratulating them on their work.