Like her late mother, Milagro Navarro, a fearless horse-riding stunt performer from Miradero, a small town on the edge of the wide-open frontier, Lucky isn’t exactly a fan of rules and restrictions. She has grown up in an East Coast city under her aunt Cora’s watchful eye, but when Lucky presses her own luck with one too many risky escapades, Cora picks up stakes and moves them both back with Lucky’s father. Unimpressed with the sleepy little town, Lucky has a change of heart when she meets Spirit, a wild Mustang who shares her independent streak, and befriends two local horseback riders. When a heartless horse wrangler and his team plan to capture Spirit and his herd and auction them off to a life of captivity and hard labor, Lucky enlists her new friends and bravely embarks on the adventure of a lifetime to rescue the horse who has given her freedom and a sense of purpose, and has helped Lucky discover a connection to her mother’s legacy and to her Mexican heritage that she never expected.