Meet Billie Jo Kelby, a fourteen-year-old girl living in Cimarron County, Oklahoma with her mom, a homemaker, and her dad, a farmer. While there's peace in their small family, she hasn't exactly been living the dream. Her dad was expecting a boy and got her instead, which has kept their relationship strained, and on top of that, his farm is in decline due to the drought and dust storms. Things are about to change in a big way, though, as Ma has recently learned that she's going to have a baby.
Ma taught Billie Jo to play the piano when she was young, and it's since grown into a huge passion for her. Arley Wanderdale, a music manager who gives lessons at her school, takes a special interest in her talent, inviting her to play for local shows and even go on tour with him, his band the Black Mesa Boys, and crooning heartthrob Mad Dog Craddock. In spite of her shared love for the piano, though, Ma is kind of cagey about her playing professionally, which creates tension between the two of them.
Just when things are opening up for Billie Jo's own music career, tragedy strikes. While making breakfast, Ma mistakes a bucket of kerosene for water and pours it on the stove. She runs outside with the intention of coming back in, but Billie Jo, unaware of this, throws the flaming bucket of kerosene outside at the moment she returns, catching Ma on fire.
Billie Jo tries to smother the flames with her hands, badly burning them in the process. A few days later, Ma dies giving birth to a baby boy, whom Daddy names Franklin (as in Roosevelt). Billie Jo struggles with anger toward both herself and Daddy for what happened.
Billie Jo and Daddy struggle to fill the void left by Ma and the baby. Daddy starts digging an enormous hole for an irrigation pond Ma suggested he try to make and enrolls in some night school classes in case the farm goes under; meanwhile, Billie Jo attempts to find ways to break the silence between them and deal with her emotions about what happened. Life, however, is one giant, constant reminder of what she's lost, especially when a migrant family joins her school and the mother gives birth to a baby girl.
While her hands are in such pain that playing piano is difficulty, Billie Jo still tries. She accepts Arley's invitation to play at a dance show and even wins third prize in a talent competition. Even music, though, has lost the joy it used to bring her; life eventually wears her down so much that when she's invited to play at graduation ceremonies, she only sits there and can't play a note.
We'd like to say that things gradually start getting better for Daddy and Billie Jo, but they don't. Daddy's wheat crops continue to experience the onslaught of the dust storms, and although his own father died of skin cancer, Daddy chooses to ignore some spots that start showing up on his skin rather than get them treated. When Billie Jo realizes that he would rather die and abandon her than continue to face the future without Ma, she decides to leave home.
Billie Jo hitches a ride on a boxcar traveling west, and on her journey, she meets up with a man who left his wife and children in hopes of finding a better way to provide for them. Her encounter with the man makes her realize that getting away from Oklahoma isn't the answer—she can't abandon her father and the only home she knows—instead she needs to learn to grow there, just like the wheat. She gets off the train in Arizona and places a call to the local store for someone to let Daddy know she's coming home.
Daddy meets her at the station and things immediately begin to improve. They start talking openly about everything that's happened and Billie Jo convinces him to get his skin examined. The doctor cuts out the spots in hopes of stopping the cancer, and advises Billie Jo to start using her hands again to help them heal.
Just as Billie Jo and Daddy start to heal their relationship, another big development happens: Daddy's lady friend, Louise, comes to dinner. She was his teacher in the night school class and the two really hit it off. While she's happy for her dad, Billie Jo struggles with how much she wants to let Louise into her life; Louise is understanding of this though, and doesn't try to force her way into the family. Instead, she kindly listens to Billie Jo's story and gradually wins her over.
On Thanksgiving, Daddy asks Louise to marry him. She gives him a second mule for an engagement gift, and he makes plans to diversify his crop selection and try some new farming techniques. Billie Jo loves Louise and looks forward to her visits, as well as the day she and Daddy get married. She enjoys playing piano for them, having finally let herself heal enough to return to her love of music.