In Mexico's Copper Canyon, where Pancho Villa once eluded George S. Patton and cartels now tend their crops, there lives a tribe who eat mice, inhale corn beer, and run distances that would leave Dean Karnazes whimpering in a support vehicle. Ever since seven cape-and-sandal-clad Tarahumara Indians obliterated a field of PowerBar eaters at the 1994 Leadville Trail 100 ultramarathon, the running world has been obsessed with the athletes, who responded to the attention by disappearing. In this book, which is equal parts quest, physiology treatise, and running history, McDougall, an enthusiastic but oft-injured jogger, seeks to learn the secrets of the Tarahumara the old-fashioned way: He tracks them down. His guide is a gringo expat named Caballo Blanco ("White Horse"), who dreams of arranging a showdown between the Tarahumara and America's top ultra-runners. Improbably, this happensthe White Horse lures six endurance stars, including Scott Jurek, to race the Tarahumara on their home turf. Spoiling the ending would be criminal, but I'll say that the climactic race reads like a sprint, which is remarkable, since the author spends all 50 miles wheezing at the back of the pack. When McDougall writes of the Tarahumara, "They remembered that running was mankind's first fine art, our original act of inspired creation," it doesn't feel overwrought. It simply makes you want to run.