Cousins Alison and Becky travel to Wyoming along with their friend Meg to spend their school holiday on a horse ranch, but Alison's foul mood threatens to make the week more a trial than a treat until she finds purpose in caring for a sick wild horse.
Friends Alison, Becky, and Meg, spending the summer at Mustang Mountain Ranch with Becky's parents, become involved in saving the wild horses of the area from a bounty hunter.
After Ruby, the owner of a neighboring lodge, gets sick, Meg and Thomas decide to help her and watch after her ten-year-old son, Tyler, who releases ranch horses that Thomas gets lost trying to find.
Becky enters her first endurance challenge, a fifty-mile race over difficult mountain trails, confident in her friend Rob's help, but jealousy threatens her chances when Rob is distracted by a willowy blonde--and soon she realizes some of the riders will stop at nothing to win.
Young horse lover Meg O'Donnell can hardly wait to start her summer at Mustang Mountain, but a sudden storm on the way there leaves her, two other girls, and their driver struggling to survive the elements.
Meg, Alison, and Becky, alone at Mustang Mountain Ranch after Becky's mother is hospitalized, put themselves in serious danger when they attempt to rescue two missing horses in the midst of a forest fire.
