A general summary of To Kill a Mockingbird would have to include the main characters, a few important events, and one or more prominent themes.
The book is told from the perspective of a young girl, Scout, but it is narrated by her as an older woman. She lives with her brother Jem, her father Atticus, and their housekeeper Calpurnia in a small town (Maycomb) in 1930s Alabama. Atticus is a lawyer and public defender. The largest public event in the novel is the trial of a black man, Tom Robinson, in a southern town which still has strong racist attitudes. Atticus is Tom's trial lawyer. While this event dominates the public sphere of Maycomb, the novel is driven by Scout's perception of things and is therefore a bildungsroman, or coming of age tale. With Atticus as the moral backbone of the community, Scout learns firsthand how to deal with the racism, injustice, and the conflicted world of adults as she matures into a young woman. the novel delves into social issues, maturity, and the social and psychological factors that affect perception.
As Scout matures, she learns to consider things from all angles and all perspectives. In Chapter 31, she narrates:
Atticus was right. One time he said you never really know a man until you stand in his shoes and walk around in them.
Seeing things from the perspective of others teaches her that "having perspective" means understanding differing viewpoints, understanding events and people in broader social/historical contexts, and it teaches her how to be sympathetic.