Young colt Sky was born with the urge to run. Alongside his band, he moves across the range searching for fresh water and abundant grazing. But humans have begun to encroach on Sky's homelands. With fewer resources to share, Sky knows that he must leave if his family is to survive. He hopes that one day, he'll be strong and brave enough to return and challenge the stallion to lead the herd. Being a lone wild horse in a vast landscape is not easy, and things get even more dangerous when Sky is captured and forced to run for the Pony Express. Now, against all odds, Sky must find a way to escape and reunite with his family.