Harper Lee's iconic coming of age story To Kill a Mockingbird is a classic. It tells the story of two children being raised by their father, Atticus (a widower), and their housekeeper, Calpurnia. It is through Scout's eyes that the reader sees the world of the South during a time when race was used as a measuring stick to judge a person's worth. Many whites in the fictional town of Maycomb, Alabama, judge a man by the color of his skin, not by his character. One of the most outstanding exceptions to this is Atticus—a lawyer who believes in "justice for all." He decides to defend Tom Robinson, a black man wrongfully accused of raping a white woman, Mayella Ewell—even though his chances of winner are poor.
The first set of main characters are Scout and her father, their housekeeper, Jem (her brother) and a new kid visiting his aunt for the summer named Dill.
The children spend several summers together throughout the book, getting into mischief. One particularly fascinating member of the community is the reclusive Boo Radley. Too much of what they "know" comes from gossips in town. They hear he is savage (eats animals raw) and has to be locked up during the day in his house. They make it their mission to get Boo to come out of the house.
Dill said, "It's my idea. I figure if he'd come out and sit a spell with us he might feel better."
"How do you know he don't feel good?"
"Well how'd you feel if you'd been shut up for a hundred years with nothin' but cats to eat?"
They spend a lot of time trying to avoid Atticus' attention, as he has told them to leave Boo alone.
Scout and Jem get into trouble with Mrs. Dubose one day when she speaks harshly about Atticus for defending a black man. Jem becomes enraged and destroys her flowers. In punishment, he must read to the ailing woman everyday. They learn she had a morphine addiction for pain that she wanted to break before she died, and Jem's reading helped distract her. After her death, Atticus explains this and says of Mrs. Dubose:
She was the bravest person I ever knew.
The children learn from Atticus and Miss Maudie to protect things that are harmless.
[Atticus said] “…but it’s a sin to kill a mockingbird.”
That was the only time I ever heard Atticus say it was a sin to do something, and I asked Miss Maudie about it.
“Your father’s right,” she said. “Mockingbirds don’t do one thing but make music for us to enjoy. They . . . sing their hearts out for us. That’s why it’s a sin to kill a mockingbird.”
This is a central theme in the book: Tom Robinson and Boo Radley are "the mockingbirds" in the story that are harmed.
When the court trial comes to an end, it is obvious that Tom is innocent, but...
In the secret courts of men's hearts Atticus had no case. Tom was a dead man the minute Mayella Ewell opened her mouth and screamed.
Tom is convicted, and later killed trying to escape.
The kids learn to better understand Boo (and others) when Atticus instructs:
You never really understand a person until you consider things from his point of view—until you climb into his skin and walk around in it.
At the end, the children get their wish to meet Boo. On the way home after a school pageant, Bob Ewell tries to kill them to get back at Atticus. It is then that Boo (who has been watching the children) fends off their attacker, kills him and saves the children, taking them home.
See the eNotes summary for more details, at the link below.