When Jon Krakauer reached the summit of Mt. Everest in the early afternoon of May 10, 1996, he hadn't slept in fifty-seven hours and was reeling from the brain-altering effects of oxygen depletion. As he turned to begin his long, dangerous descent from 29,028 feet, twenty other climbers were still pushing doggedly toward the top. No one had noticed that the sky had begun to fill with clouds. Six hours later and 3,000 feet lower, in 70-knot winds and blinding snow, Krakauer collapsed in his tent, freezing, hallucinating from exhaustion and hypoxia, but safe.