Janey Larkin is ten years old when her family arrives in the San Joaquin Valley of California. She is an only child and lives with her father and stepmother, her mother having died years earlier. Janey notices that there is a family across the road and that there's a girl about her age, Lupe Romero. She wants to seek out Lupe's friendship but knows that the Larkin family never stays anywhere long so there probably won't be time to develop a friendship. Janey doesn't go to meet Lupe but is excited when Lupe makes the first move. The first thing Janey shows Lupe is her one important possession - a blue willow plate. The plate pictures a stand of willow trees, a river, a bridge and three people. Janey tells Lupe the story of the plate as it's been told to her. Though Lupe doesn't understand the importance - that the plate represents Janey's life prior to the family's financial hardships and the hope of a better life - she understands that it's important to Janey. This respect for each other is the heart of the girls' friendship, which grows over the coming months.

Janey is invited to go with the Romero family to the fair and she's elated with the opportunity. Her mom gives her a nickel to spend and Janey buys gum to share with the others. She is most excited at the fair to see a large display of books, and she pleads for the opportunity to remain there to read. Later, Janey goes to school with the other children from the farm camp. She finds a friend in the teacher, Miss Peterson, and learns that even a ragged book can become an escape from life, taking her on exciting adventures.

Meanwhile, Janey and her family know their time at the little shack that's become home is limited. The land belongs to Mr. Anderson, a kindly man Janey meets only once during their three-month stay. A foreman on the farm, Bounce Reyburn, demands a monthly payment of five dollars for rent. The rent straps the family's limited cash and Mr. Larkin announces that with the harvests gone, it's time for the family to move again. Bounce demands yet another month's payment - money the family doesn't have. Janey gives Bounce the plate in place of the rent. Bounce, recognizing that the plate is important to the family, accepts.

The day before the family is to leave, Janey goes to Mr. Anderson's house. She hopes to see the plate one last time before the family departs. Mr. Anderson doesn't know about the plate or the rent that Bounce has collected. He is angry at the deception of his foreman and fires Bounce, returns the rent collected from the Larkins and hires Mr. Larkin as his new foreman, which means the family will no longer have to move in search of work. One day Janey learns that Mr. Anderson is building a larger house for the Larkins. When the house is finished, Janey asks the question that's been haunting her, "How long can we stay?" Mr. Larkin assures her that they can stay as long as they want.