The place: Maycomb, Alabama, finalist for the Most Boring Town in America. Few people move in, fewer move out, so it's just the same families doing the same things for generation after generation. Like the Finches: Scout, her brother Jem, and their father Atticus. Every summer Scout and Jem are joined by Dill Harris, who shares their obsession with the local haunted house, the Radley Place, and the boogeyman who lives there, Boo Radley.
Fall comes, Dill leaves, and Scout starts school. The Radley Place is in between Scout's house and school, so she has to go by it every day, usually at top speed. One day she notices something odd: a couple of pieces of gum stuck in a hole in the tree. She tells Jem about it, and soon they find other treasures hidden in the same place, including finely-carved soap figurines of Scout and Jem themselves. This lasts until the following fall, when they find that Mr. Nathan (Boo's brother) has filled in the knothole with cement.
That winter, disaster strikes: Miss Maudie's house catches on fire and burns to the ground. While a sleepy Scout stands on the street trying not to freeze, someone drapes a blanket over her shoulders without her noticing: turns out that someone was Boo Radley, and it freaks Scout out that he was right there and she didn't even notice.
At school, Scout gets flak from her classmates because her father, a lawyer, has taken on a new client, a black man named Tom Robinson. Over the summer, Jem and Scout learn important lessons about race (black people don't much like white people; their black cook has a whole life and world of her own), and they also learn that Tom Robinson's been accused of raping a white woman. Oh, and meanwhile Aunt Alexandra has shown up to teach the kids some family pride and, in Scout's case, ladylike behavior. Good luck.
Finally, it's the day of Tom Robinson's trial. The kids sneak over to see, and it's pretty apparent (to us, at least) that the white woman, Mayella Ewell, is lying. Great! Truth and Atticus's lawyering skills win the day, right? Not so much. Tom is convicted, and some of the white folks aren't too happy about Atticus basically accusing the girl and her dad of lying. Then, a few weeks later, Tom is dead, shot while trying to escape prison.
As if things aren't bad enough, Jem and Scout hear rumors that the girl's dad has been indirectly threatening their dad. One dark night, they're on their way back home from the school's Halloween pageant when they hear someone following them. Suddenly they're attacked, though Scout can't see much because of her costume. When things calm down, one man is on the ground, and another carries the injured and unconscious Jem back to the Finch house, while Scout follows.
When all the excitement dies down, it turns out that Mr. Ewell (the girl's dad) is dead, Jem's arm is broken, and Boo Radley is the one who carried Jem home. For some reason, Atticus assumes that the killer is the 10-year-old boy rather than the silent, hulking giant, and he starts planning Jem's legal defense. Luckily, a friend talks him out of it. The novel ends with Scout looking at her neighborhood with new eyes from the Radley front porch, wondering what Boo thinks about all this.
And then she goes home to have her daddy tuck her in and read her to sleep.