Scout explains that when her brother, Jem, was 13, he broke his arm. Many years later, they argue about when everything that led to the accident truly began. Jem maintains that it began the year Dill arrived, while Scout insists that they take a broader view. She gives a brief account of her family’s history—her ancestor Simon Finch who left England to escape religious persecution and established a modest plantation called Finch’s Landing. The Finches remained on that land until Scout’s father, Atticus, and his brother left to study law and medicine, respectively. Atticus set up shop in Maycomb, 20 miles away from Finch’s Landing, and is related to nearly everyone in the county. When the story begins, Maycomb is a tired and poor old town, and Scout’s family lives on the main residential street.
The opening of the novel effectively establishes a foundation for many of its themes. That Simon Finch had to leave England to escape religious persecution points to the existence of prejudice. But that Simon finds success and establishes a "plantation," which implies that he and his descendants owned slaves, points to the complications of good and evil: Simon who suffered prejudice goes on to build his fortune by practicing his own prejudice upon others. (That Atticus left the plantation to make his living also implies that Atticus' views about race and slavery differ from those of his ancestors.) Meanwhile, the fact that Atticus—and by extension, Jem and Scout—are related to most people in the county speaks to the nature of small-town Southern life: Maycomb is a close-knit and insular community. Scout's description of the town as old and tired further establishes the setting in which the story takes place—the Great Depression. Scout's language to describe the town also accomplishes something else, as well. A child is unlikely to either perceive or describe her hometown as being "tired." Scout's language, then, makes clear that Scout functions in the novel in two ways: as the child who is its main character, but also as the grown up narrator looking back on her younger self with more knowledge, more wisdom. Even though the adult narrator spends much of the book speaking through the voice of her younger self and describing the world through her younger self's eyes, by establishing both the child and adult Scout as presences right from the beginning, the opening of the novel introduces the idea that this will be a novel about young Scout's growing into her older self.
Scout and Jem love Atticus, but their cook, Calpurnia, is a mystery. Since Scout’s mother died when Scout was two, Calpurnia raises Scout and Jem and Scout finds her tyrannical. When Scout is six and Jem is 10, they spend their summer playing on their block and, one morning, they find a boy sitting in Miss Rachel’s collard patch. He introduces himself as Charles Baker Harris, or Dill, and announces that he’s almost seven and can read. Dill is from Mississippi and is spending the summer with his aunt, Miss Rachel. He explains that he saw the film Dracula, which endears him to Scout and Jem. After this, they spend the summer in their tree house and performing their various dramas based off of their favorite books. By August, though, they’re bored, and Dill turns his attention to the Radley Place.
Scout likely finds Calpurnia tyrannical and one-dimensional because she’s so young and can’t yet understand Calpurnia as a complex individual. Dill and his imagination begin to situate these kinds of fantasy games as a hallmark of childhood in Mockingbird, while the fact that their games are based off of books indicates that all three children are literate. While this might not seem important to the children themselves, it does point to their financial situation and Atticus’s professional job, as they have enough money to live in a home that encourages education.
The Radley Place is a low house in disrepair two doors down. A phantom lives inside and commits petty crimes, and children believe everything on the property is poisoned. The Radleys keep to themselves, something unheard of in Maycomb. According to legend, the youngest son, Arthur “Boo” Radley, joined a gang in his teens, participated in tormenting a parish official, and rather than allow his son to attend the industrial school, Mr. Radley kept Boo at home from then on. Then—according to the neighborhood scold, Miss Stephanie Crawford—when Jem was little, Boo stabbed his father with scissors. Jem figures that these days, Boo lives chained to his bed. Mr. Radley died soon after and Calpurnia whispered that he was mean, which surprised Jem and Scout—she never speaks ill of white people. Nathan Radley returned to the house to imprison his brother. All of this fascinates Dill.
The beliefs that a phantom lives in the house and that everything is poisoned is clearly the work of young imaginations. But note where those rumors likely stem from: the Radley family is considered strange and even evil because they don’t socialize like most people in Maycomb. The particulars of Boo being kept at home, coupled with Calpurnia’s posthumous assessment of Mr. Radley’s character, suggests that the reason for their seclusion may have been abuse, but this seems to be beyond the children’s understanding.
Jem entertains Dill by describing what Boo looks like: tall and scarred with yellow teeth and fed on a diet of raw cats and squirrels. Dill decides he’d like to get a look, so he dares Jem to touch the house by goading and insulting him. Jem takes his time but races to the house, slaps the siding, and then races back to the safety of his own porch with Dill and Scout behind him. The children notice a small movement in the window.
Jem’s very real anxiety about touching Radley Place makes the case that as people ostracize others for being different and as rumors circulate, this inevitably turns into not an understanding of difference, but a genuine fear of people who are different. That this shows up in a child rather than an adult, however, does offer hope that Jem will be able to question this later.