Fifteen-year-old Kellea Sullivan watches as county officials remove five thin, shaggy horses from a mud-mired yard, to take the animals to a nearby sanctuary. As the officers pull away, a foal races from behind the house, and Kellea races to catch up and let the officers know. While she watches the officers rein in the horse, Kellea is strongly attracted to the foal. Over the next few days, Kellea works out a plan to spend her summer working a the sanctuary to be near the foal and help take care of him. A bond develops between the two, and she names him Wind-Free because of his amazing ability to run as fast as the wind.
Learning the Thoroughbreds originally lived in Virginia and were stolen, Kellea meets their owners, Michael and Elizabeth O'Brien, who come to Texas to claim the horses. The O'Briens, who are aware of the love Kellea has developed for Wind-Free, invite her to their farm over the holidays. She learns more about caring and training horses for racing, and decides she wants to be a professional trainer. Over the next few years, Kellea spends holidays and summer vacations working with Wind-Free, even caring for him when he is accidentally caught in a trap. Finally, when Wind-Free is 3 years old, and in spite of past injuries, the O'Briens and their veterinarian determine he is ready to run in the Kentucky Derby.
Will he live up to his name and reap great rewards? Or will another injury put him out to pasture for good?