In the opening pages of Finders Keepers, the 2015 sequel to Stephen King's 2014 novel, Mr. Mercedes, Morris Bellamy breaks into the home of his favorite author, John Rothstein. From there, the plot escalates to murder, and then to a theft with consequences years later.
In 1978, Bellamy, already established as a petty criminal and accompanied by two chums, breaks into the home of John Rothstein to steal his money. However, Bellamy also takes a personal issue with Rothstein for his Jimmy Gold series. Being an extreme fanatic of the trilogy, Bellamy is disgusted with the final book's conclusion of Jimmy Gold settling down and entering a job in advertising ("chasing the Golden Buck", as Bellamy calls it). Rothstein holds his ground, but Bellamy kills him in a fit of rage. Bellamy and his colleagues steal not only Rothstein's money, but also several Moleskine journals containing several fragments written in the duration of Rothstein's seeming retirement, including two future installments of Jimmy Gold's story. Driven by paranoia and a jealous possessiveness of the books, Bellamy murders his two colleagues and gets away with committing the murder. He purchases a steamer trunk to stow away the money and notebooks, burying it under the exposed roots of a tree by his home. However, Bellamy is later arrested when he gets drunk and violently rapes a woman-a crime he does not recall doing.
In 2014, Bellamy is released on parole and sets out to unearth the trunk, while trying to not arouse suspicion from his parole officer. However, the trunk had been found and uncovered by Peter Saubers, whose family now lives in Bellamy's old home. Saubers steadily takes out the money and mails it anonymously to his parents, to stablize their household following his father's severe injuries caused by Brady Hartsfield's attack in the Mercedes. Wanting to help his sister, Tina, attend a private school with her friends, Peter tries to sell the Rothstein notebooks-after reading and becoming a fan of Rothstein's works. Unfortunately, he unwittingly endangers himself and his family when he tries to sell them to a bookstore owner and former colleague of Bellamy's, who recognizes the Rothstein excerpts and blackmails Peter.
On the date when Peter is set to effectively surrender the Rothstein notebooks to him, Bellamy pays his old associate a visit and murders him for the notebooks. Using the bookstore's locale and security equipment, Bellamy attempts to capture and force Peter to hand over the Rothstein notebooks. When Peter refuses, Bellamy tries to shoot him, only to be warded off by Peter throwing the bookstore owner's decanters at him. Peter escapes, but is further blackmailed by Bellamy threatening to frame Peter for the murder he committed. Unbeknownst to Bellamy, Peter relocates the notebooks in an old rec center's basement.
Worried that her brother might be in trouble, Tina informs Detective Hodges and Holly, the protagonists of Mr. Mercedes, about Peter's behavior. After making a connection with him, Hodges fails to catch Peter before he tries to run home, fearing that Bellamy will hurt his family. His worst fears are confirmed when Bellamy abducts Tina and non-fatally shoots their mother. Peter is forced to come to the rec center, but brings along his father's lighter and lighter fluid. While Hodges comes to help, Bellamy is brought down when Peter sets the Rothstein notebooks on fire. Unwilling to let them go, Bellamy is incinerated when he hopelessly tries to save the notebooks.
Bellamy is marked by his fanaticism. To him, Jimmy Gold was an idol, and to see him "chase the Golden Buck" at the end drove him over the edge. Throughout the novel, he demonstrates a psychopathic willingness to hurt anyone, if it means that he'll be able to collect and read the notebooks. This is horrifically observed when he murders his former colleagues out of paranoia that they may sell off and deny him the chance to read these works. There's also his treatment of Tina, forcing her to walk to the rec center at gunpoint and smacking her when she protests. He also makes it very clear that he intends to kill her if Peter doesn't comply. Nevertheless, this fanaticism is his own undoing, as it leads to his death.
Somewhat tragic, being a frequent rape victim in prison, Bellamy is also marked by his refusal to accept responsibility for his actions. He blames his mother throughout his life for not understanding things as he does, and then pins the blame for Rothstein's death on himself for "ruining" Jimmy Gold. Bellamy also demonstrates a homophobic side, mentally belittling his book-vending associate for being gay and conniving.