Run Free: The True Story of Caballo Blanco 2015 Synopsis - American ultra running legend Micah True (Caballo Blanco, or the White Horse) lived and ran with the Tarahumara Indians in Northern Mexico. The Tarahumara (also known as the Rarámuri or the Running People) are some of the best long distance runners in the world. This award-winning feature-length documentary chronicles Micah's quest to promote and preserve Tarahumara running tradition by creating a 50-mile foot race known as the Copper Canyon Ultra Marathon, which was portrayed in Christopher McDougall’s best-selling book "Born to Run – A Hidden Tribe, Super Athletes and the Greatest Race the World Has Never Seen".