In Canton, Mississippi, 10-year-old Tonya Hailey is viciously raped and beaten by two white racists—James Louis “Pete” Willard and Billy Ray Cobb. Shortly thereafter, Tonya is found and rushed to a hospital, while Pete and Billy Ray are heard bragging in a roadside bar about what they did to Tonya.
Tonya’s distraught and enraged father, Carl Lee Hailey, recalls a similar case from the year before, in which four white men raped a black girl in a nearby town and were acquitted. Carl Lee is determined not to allow that to happen in this case. Consequently, while Deputy DeWayne Powell Looney is escorting Pete and Billy Ray up a flight of stairs inside the courthouse, Carl Lee emerges from a nearby closet with an assault rifle and kills Pete and Billy Ray and accidentally wounds Looney, resulting in the amputation of his lower leg. (During the trial Looney forgives Hailey, saying he has a daughter himself, and that if someone raped her, he would gladly do the same as Carl Lee.)
Carl Lee is later arrested at his home by the highly respected, honorable and beloved black county sheriff Ozzie Walls (who must uphold the law but, as the father of two daughters of his own, privately supports what Carl Lee did and gives him special treatment while in jail) and charged with capital murder. Despite the efforts of the NAACP and his old military friend Cat to persuade Carl Lee to retain their high-powered attorneys, Carl Lee elects to be represented by his friend, Jake Tyler Brigance. Helping Jake on the case are his two most loyal friends—his heavy-drinking former boss Lucien Wilbanks (who has since been disbarred for his involvement in a fight resulting from a union strike, but still consults and aides Jake from the background), and sleazy divorce lawyer Harry Rex Vonner. Later, the crew is joined and greatly assisted by rabid ACLU feminist and law student Ellen Roark, who has prior experience with death penalty cases and offers Jake her services for free as a temporary clerk for the duration of the case. Ellen appears to be interested in Jake romantically, but Jake resists her not-so-subtle overtures and is completely loyal to his wife. The prosecuting attorney is Rufus Buckley, a corrupt shark with no concern or respect for ethics and with sky high political ambitions, hoping to win the case so as to gain the publicity that a win would generate, in hopes of being elected to a higher public office (governor). To annoy Buckley and call attention to this fact, Jake often addresses the D.A. as “governor” in pre-trial conferences. Presiding over the trial is white (but generally impartial) judge Omar “Ichabod” Noose. It is claimed, however, that Noose has been intimidated, both politically and criminally, a rumor given significant merit when, despite having no history of racist tendencies in his decisions, he refuses Jake’s perfectly reasonable request for a change of venue, further handicapping the defense, as the racial make-up of Ford County virtually guarantees an all-white jury.
At the same time, Billy Ray Cobb’s brother, Freddy Lee Cobb, is seeking revenge for Carl Lee’s killing of his brother. To this end, Freddy enlists the help of the Mississippi branch of the Ku Klux Klan, which is led by Mississippi grand dragon Stump Sisson. Subsequently, a KKK member attempts to plant a bomb under Jake’s porch but is thwarted by the sheriff and a deputy after they receive a tip-off from a confidential informant (apparently inside the Klan) going by the code name “Mickey Mouse.” The informant is later exposed and murdered by the Klan, and it is revealed that he was a former client of Jake’s and a frequent patron of the coffee shop where Jake has long dined every morning and has become something of a folk-hero there. After the thwarted bombing, Jake sends his wife and daughter out of town to his wife’s parents’ home until the trial is over and begins spending most nights either in his office or at Lucien’s house. Later, Jake’s secretary Ethel Twitty and her frail husband Bud are attacked by the KKK, killing Bud. On the day the trial begins, there is a riot outside the court building between the KKK and the area’s black residents, and Stump is killed by a molotov cocktail. Believing that the black people were at fault, Freddy and the KKK increase their attacks. As a result, the National Guard is called to Clanton to keep the peace during the trial. Undeterred, Freddy continues his efforts to get revenge for Billy Ray’s death. They shoot at Jake one morning as he is being escorted into the courthouse, missing Jake but seriously wounding one of the guardsmen assigned to protect Jake. They continue to burn crosses throughout Canton, and Jake’s house is burnt down while Jake is sleeping at Lucien’s.
The case proceeds, and after reeling from the loss of his house and the revealing of a decades-old (and long-expunged) criminal conviction of the defense’s psychiatrist whom Jake had called to testify to Carl Lee’s “temporary insanity” at the time of the killings, Jake perseveres. He badly discredits the state’s expert doctor in a powerful and snarky cross-examination in which he establishes that the doctor has never conceded to the insanity of any defendant in any criminal case in which he has been asked to testify, even when multiple other doctors have been in consensus otherwise. He traps the doctor with a revelation that several previous defendants found insane in their trials are currently under his care despite his having testified to their “sanity” in their respective trials. Eventually the doctor loses any favor with the jury when Jake frustrates him to such an extent that he blurts out “You just can’t trust juries!” Jake follows this up with his own captivating closing statement (ignoring Lucien’s advice to use a statement he had prepared for Jake). After lengthy deliberations during which a massive pro-acquittal demonstration is held, the jury acquits Carl Lee by reason of temporary insanity. Carl Lee returns to his family, and the story ends with Jake, Lucien, and Harry Rex having a celebratory drink before Jake is to hold a press conference and then leave town for a while to reunite with his wife and daughter.
One major difference between the novel and the film adaptation is the powerful closing argument. In the film, the visual and graphic story is told by Jake Brigance, along with imploring the jury to imagine that the victim was white. However, in the book, Jake and Harry Rex discover through a post trial interview that a woman on the jury made that speech during jury deliberations. There is, in fact, a bit of a recurring theme throughout the book in that Jake is about the only character who does not appear in any way to see the case through a racial lens. He repeatedly refuses to play the “race card” even when baited to do so by several reporters, is clearly much more politically conservative than an attorney arguing such a case at the time might have been expected to be, and seems to see the situation (and thus approaches the case) only from the perspective of the father of a daughter whom he, too, would kill to protect.