Frankie Addams is a young, confused twelve-year-old adolescent living in the American south in 1944. The book is framed around her main frustration with feeling like she belongs to no group, that she is disconnected with the world around her. The daughter of a jeweler and a mother who died in child birth, she is highly precocious and stubborn, but also naïve and unaware of the reasons for her own emotions. She spends the main action of the book, which begins on the last Friday in August and ends two days later, obsessed with her brother Jarvis's wedding on Sunday to Janice Evans.

As the story begins, she expresses her fears, anxiety and confusion about marriage to her housekeeper, Berenice and her six-year-old cousin, John Henry. Berenice passes off her feelings as masked jealousy. Frankie later asks John Henry to sleep over, claiming he looks scared. However, as we know, Frankie is really the one who feels that way. She is relieved to have a person to sleep next to, since she used to sleep next to her father, until he recently said she was too old.

In the first part of the novella, the narrator describes the following Saturday morning, but then skips right to the early evening of that day. Only in the second part does McCullers return to Saturday afternoon to describe the events that took place. Before then, we are given a lot of character background about Frankie. We hear about her various attempts to become more worldly, to pay attention to things like the fact that World War II rages all around her. Through her various brushes with sexual experiences, we discover how completely unaware of the facts of life she is. Eventually, Frankie has a revelation that she belongs to her brother and his future wife, saying, "They are the we of me."

When the narration returns back to Saturday afternoon, we find that Frankie has changed her name to F. Jasmine in an attempt to both sound more grown up and to have a name which begins in J A, just like Janice and Jarvis. She tours the town telling people of her plans to run away with the newly-weds the following evening. She expects everyone to notice the sudden change in her and that she has shed her childhood persona. However, her father takes no notice and treats her as the same little girl. When she stops in his jewelry shop, he tells her that Uncle Charles has died and she tries to react in a mature manner. Walking down the street again, she encounters a Soldier and has a stilted conversation with him at a local bar, eventually agreeing to have a proper date with him later that evening.

Returning home, she sits down to eat a lengthy dinner with Berenice and John Henry. The three of them launch into a frank and heart felt conversation about love. Berenice tells of her four marriages and cautions F. Jasmine not to be delusional about her prospects of joining up with Janice and Jarvis after the wedding. They discuss what they would do were they God and could change the world to their liking. John Henry imagines a world make of good things to eat. Berenice sees a place where there is no distinction between black and white. F. Jasmine imagines that boys could change into girls and vice versa, at will. Eventually, F. Jasmine and Berenice come to a poignant understanding of the societal pitfalls of race differences.

F. Jasmine leaves the house Saturday evening and travels to Big Mama's house to have her fortune told. She learns that she will indeed take a journey the next day, but that she will eventually return. Discouraged, F. Jasmine goes to meet the soldier at the bar. They sit down for a drink and eventually he coerces her to return to his hotel room where he attempts to have sex with her. She hits him over the head with a pitcher and flees back to her house.

The wedding turns out to be a bust for the newly dubbed "Frances." She pleads to run off with Janice and Jarvis, entirely in vain. Dejected and depressed, she returns home with her hopes dashed. She attempts to run away, stealing her father's pistol, but she is quickly found by the police and returned home.

In a speedy denouement, McCullers describes the next three months. In that time, much changes for Frances. She finds a new friend, Mary Littlejohn. She and her father get ready to move. Berenice decides to quit and get married again. John Henry dies of meningitis.