The readers follow McDougall along his journey from his initial meeting of a few tribesmen, witnessing firsthand their superhuman ability, to his search for Caballo Blanco - a strange gringo, friend of the Tarahumara, living alone in the canyons and modeling their way of life. Caballo is set on organizing a race in the Tarahumara homeland for those who embody the spirit of these running people. Finally we follow the trek to the Copper Canyons for the race itself with an unusual group of ultrarunners, for the world’s greatest race the world has never seen...