Almost a century ago, while descending this ridge, Irvine and his climbing partner, George Mallory, vanished. Since then the world has wondered whether one or both of them could have made it to the top that day, 29 years before Edmund Hillary and Tenzing Norgay were recognized as the first to stand on Everest’s summit. Irvine was thought to have been carrying a Vest Pocket Kodak camera. If that camera could be found, and it held snapshots of the summit, it would rewrite the history of the world’s tallest peak.