Sixteen mustangs, four men, one dream: to ride border to border, Mexico to Canada, up the spine of the American West. The documentary tracks four fresh-out-of-college buddies as they take on wild mustangs to be their trusted mounts, and set out on the adventure of a lifetime. Their wildness of spirit, in both man and horse, is quickly dwarfed by the wilderness they must navigate: a 3000-mile gauntlet that is equally indescribable and unforgiving.…