The action of To Kill a Mockingbird centers around the narrator and protagonist of the story, young Scout Finch. The story takes place over a two and one-half year period, beginning when Scout is five. Her father, Atticus, is a prominent attorney in their small town of Maycomb, Alabama; he is a single parent whose wife died of a heart attack, leaving him to bring up Scout and her older brother, Jem. The action of the first part of the novel develops around the Finch children's relationship with summer visitor Dill Harris, and his obsession with a mysterious, unseen neighbor, Boo Radley. Boo has been unjustly accused of many bizarre events, and the children are at first terrified of him, but they still pursue their goal of getting a peek at Boo, who never leaves his house during the daylight hours. The children begin receiving gifts in the knothole of a tree on the Radley property, and they soon come to learn that Boo is harmless and wants to be their friend, too.
The second part of the novel concentrates on the trial of Tom Robinson, a black man who has been accused of raping a white woman. Atticus defends Tom, and it becomes evident to Jem and Scout--and the reader--that Tom is innocent; nevertheless, Tom is found guilty by the all-white jury. The two main plots are tied together in the end when Boo saves the children from a murderous attack by Bob Ewell, whose daughter had unjustly accused Tom of the rape. Boo kills Bob, Jem is badly injured, Scout finally gets to meet Boo, and Scout comes to realize that Boo has been a watchful neighbor, keeping an eye on her and Jem for the past several years.
The novel explores themes of racism and prejudice as a backdrop for the the youthful enthusiasm and adventures of the children, while creating an enduring character in Atticus Finch, the quintessential model of a Southern lawyer whose honesty and tolerance for all people is unmatched in American literature.