"At the age of nineteen, Lara Prior-Palmer discovered a website devoted to "the world's longest, toughest horse race"--an annual competition of endurance and skill that involves dozens of riders racing a series of twenty-five wild ponies across 1,000 kilometers of Mongolian grassland. On a whim, she decided to enter the race. As she boarded a plane to East Asia, she was utterly unprepared for what awaited her. Riders often spend years preparing to...