Jean Louise Finch, nicknamed Scout, narrates this story and it is told during the great depression of the 1930's. She lives in the town of Maycomb, Alabama with her widowed father Atticus, and her older brother by four years, Jeremy Finch (called Jem).
Scout tells us about her ancestors who originally fled England to escape religious persecution and they established a large farm on the banks of the Alabama River called Finch's Landing. The family was farmers for a hundred years until Atticus became a lawyer in Maycomb while his sister, Alexandra, ran the farm.
At the start of the story, Scout is aged 6. Scout's mother had died four years previously and their cook, an old black woman called Calpurnia, helps to bring up the two siblings.
An odd boy named Charles Baker Harris, known as Dill, moves in next door for the summer to stay with his aunt, Miss Rachel Haverford. Dill's parents are getting divorced and he is reluctant to talk about this taboo subject, but is very talkative about everything else. Coupled with his intelligence, he soon becomes friends with Scout and Jem. Their main curiosity over the summer months is the Radley house, in particular one of its strange occupants, Arthur Boo' Radley, who never comes out of the run-down house at the end of their street. .
As a boy, Boo got into trouble with the authorities and his father imprisoned him in the house as a punishment. Nothing much was heard about him until fifteen years later when he stabbed his father with a pair of scissors and people suggested he was a lunatic. The old Mr. Radley refused to have his son committed and when he died, his son Nathan came to live in the Radley house so that Boo would not be left alone. The run-down house is treated as a kind of haunted place and Boo is the resident ghost. .
We see here that Scout's world is based on a strong foundation of certainties, but as the story unfolds circumstances and situations arise which undermine this security.