The year is 1959 and the setting is River Valley Farm, located in Holcomb Kansas (a suburb of Garden City). The residents of that farm, the Clutters, are a prosperous farming and ranching family who have seemingly achieved the American Dream. Herb, the father, is a devout Methodist whose work ethic has made him a wealthy and popular man. Bonnie, Herb’s wife, suffers from nervousness, and it’s speculated that her marriage to Herb is troubled. Nancy and Kenyon are their well adjusted, hardworking teenage children. One night in mid-November, four gunshots ring out across Holcomb, signaling the deaths of four members of the Clutter family.
The murderers are Perry Smith and Richard “Dick” Hickok, two recently paroled men who have been led to believe that Herb Clutter is in possession of a large amount of cash. Perry is a dreamy, artistic man scarred by a motorcycle accident and his traumatic childhood. Dick is a “normal” guy with a shoddy work ethic who has a history of writing bad checks. While robbing the Clutters, Dick and Perry are dismayed to find that the Clutters have virtually no cash on hand. They kill the Clutters anyway, shooting each in the head at point-blank range with a 12-gauge shotgun. Dick and Perry flee to Kansas City, where they start writing bad checks. They take their ill-gotten gains and flee to Mexico, where Perry dreams of becoming a treasure hunter.
As news of the murders spreads, the citizens of Holcomb and Garden City are filled with terror and disbelief. The Kansas Bureau of Investigation (KBI) is put on the case, though there is little evidence to help them find the killers (all they have are two footprints). The case is finally cracked when Dick’s former cellmate, Floyd Wells (who was once an employee of Herb Clutter’s), reveals that Dick had divulged to him his plan for robbing and killing the Clutters. Armed with this lead, the KBI launches a nationwide manhunt for Dick and Perry.
Meanwhile, Dick and Perry, having gone broke in Mexico, have returned to the United States and are plotting to write more bad checks. They return to Kansas City, where they write enough bad checks to fund a trip to Florida. Tensions rise and fall between Perry and Dick. Perry is upset with Dick’s spendthrift ways, and is disgusted with his penchant for raping young girls. Dick, on the other hand, is frustrated with Perry’s “womanly” behavior and far-fetched dreams of treasure hunting. After going broke in Florida, the two make their way to Las Vegas, where months back Perry had mailed some of his belongings from Mexico (including the boots he and Dick had worn the night of the murders). They are arrested in Las Vegas, just as they stop to collect the final box of belongings from a rooming house.
A trial is held in Garden City. Dick and Perry are ultimately sentenced to death, and they are sent to Death Row at Kansas State Penitentiary. They remain on Death Row for years, given that Dick insists that their trial was unfair and applies for several appeals. Perry briefly goes on a hunger strike, during which time he’s accosted by visions of a golden parrot (an image he seems to connect with Jesus); he decides to eat again when he receives a postcard from his father that fills him with rage. Dick and Perry are hanged on April 14th, 1965. The primary investigator in the Clutter case, Alvin Dewey (a personal friend of the Clutters) is present for the hanging. The hanging doesn’t bring him closure. Instead, he finds solace in a chance meeting he had with Nancy’s best friend, Susan Kidwell, whom he runs into at the Clutter’s grave plot. Susan fills Alvin with hope for the future – she seems to represent a renewed age of innocence for Holcomb and Garden City.