At the beginning of the book, Dill, Jem, and Scout are all intrigued by Boo Radley and why he never comes out of the Radley House.
Jem and Scout's father, Atticus Finch, is tasked with defending Tom Robinson, a black man accused of raping Bob Ewell's daughter. Jem and Scout are both subjected to insults by the town because their father is defending a black man.
Despite Atticus' best defense, the racist jury of Maycomb still find Tom guilty.
Even though Tom Robinson was found guilty, Bob Ewell still felt like Atticus made him and his family look like fools in the courtroom. He swore he would get his revenge on Atticus if it took him all his life.
During Halloween, Bob Ewell tries to enact his revenge on Atticus by chasing and trying to kill Jem and Scout.
Fortunately, Boo Radley, came out of nowhere to save Scout and Jem. He fought Bob Ewell and took his knifr from him, eventually killing him with his own knife. To protect Boo, Sheriff Tate made everone agree that Bob Ewell had tripped and fell on his own knife.