If the quest for Mount Everest began as a grand imperial gesture, as redemption for an empire of explorers that had lost the race to the Poles, it ended as a mission of regeneration for a country and a people bled white by war. Of the twenty-six British climbers who, on three expeditions, walked 400 miles off the map to find and assault the highest mountain on Earth, twenty had seen the worst of the fighting. Six had been severely wounded, two others nearly killed by disease at the Front, one hospitalized twice with shell shock. Three as army surgeons dealt for the duration with the agonies of the dying. Two lost brothers, killed in action. All had endured the slaughter, the coughing of the guns, the bones and barbed wire, the white faces of the dead. In a monumental work of history and adventure, ten years in the writing, Wade Davis asks not whether George Mallory was the first to reach the summit of Everest, but rather why he kept on climbing on that fateful day. His answer lies in...