In June 1924, a British mountaineer named George Leigh Mallory and a young engineering student named Andrew "Sandy" Irvine set off for the summit of Mount Everest and disappeared—two more casualties of a peak that has claimed over 300 lives to date. Mallory's body was found in 1999, but Irvine's was never found—until now. An expedition led by National Geographic Explorer and professional climber Jimmy Chin—who won an Oscar for the 2019 documentary Free Solo, which he co-directed—has located a...