It's the summer and teenager Katy McLaughlin (ALISON LOHMAN) has returned to her family's Wyoming horse ranch after spending the year at a private academy where her lack of focus has resulted in her not being invited back the following year. She knows that her older brother, Howard (RYAN KWANTEN), will understand, especially since he'd rather head off to college with his girlfriend Miranda (KAYLEE DeFER) than raise quarter horses at the Goose Creek Ranch.
However, Katy's reluctant to tell her parents -- Rob (TIM McGRAW) and Nell (MARIO BELLO) -- since they've sacrificed so much to send her off to college so that she can have a life other than ranching. And with the local rodeo more interested in wild horses than the ones they breed, money is becoming increasingly tight.
Accordingly, rather than give them the bad news, she takes a horseback ride across their far-reaching lands where she not only encounters a menacing mountain lion, but also a wild mustang that saves her life from it. She eventually returns and tries to capture the horse for her own, an act that doesn't win any points with her father since he's since learned of her academic troubles and views wild horses as a threat to his business. As ranch hands Jack (DANNY PINO) and Gus (DALLAS ROBERTS) look on, Katy nevertheless tries to gain the confidence of the mustang she's named Flicka, and she feels an affinity with the horse as both are restless spirits.
As the summer wears on and Katy and her dad repeatedly clash over the horse, her school and more, the two eventually learn things about themselves and each other that soon redefine their relationship.