In an exclusive excerpt from the forthcoming book by the men who led the quest to solve the mystery of George Mallory's disappearance, the authors for the first time reveal the evidence they uncovered—and offer their chilling re-creation of Mallory and Irvine's last hours.

By Eric Simonson, Jochen Hemmleb, and Larry Johnson

It was the expedition that couldn't possibly succeed. A group of veteran mountaineers, headed by renowned American expedition leader Eric Simonson and guided by the research of a young German amateur historian named Jochen Hemmleb, would seek to answer exploration's most confounding mystery: What happened to George Leigh Mallory and Andrew Comyn "Sandy" Irvine, who disappeared on the mountain during their assault on the summit, on June 8, 1924?

That the 1999 Mallory and Irvine Research Expedition overshot even its own wild ambitions is by now common knowledge. The news that it had found Mallory's remains at nearly 27,000 feet on the windswept scree of Everest's inhospitable North Face startled the world this spring.

But what has not been known, because the details have not been released until now, is what the expedition discovered about Mallory and Irvine's final day. It is a story that began on May 1, as American mountaineers Dave Hahn, Jake Norton, Andy Politz, and Tap Richards crossed a vertiginous snow terrace on the North Face toward fellow expedition member Conrad Anker. At Anker's feet, frozen in a 75-year-old self-arrest, was a body whose torso was alabaster white, almost perfectly preserved. They had been searching for less than two hours. Jake Norton began scratching out a memorial stone: "Andrew Irvine: 1902-1924."

"This isn't him," Politz suddenly said.

The team looked at the body. They looked at Politz as if he were crazy.

"Oh, I think so," Anker said.

"I don't know what made me say it," Politz said later. "Here was this very old body, perfectly preserved, with very old clothing and the hobnailed boots. I knew it had to be Sandy Irvine; Irvine was who we were looking for, and that's who it had to be."

To find anything at all was unthinkable on Everest's white expanse. The area they were searching was above 26,000 feet—a wide snow terrace the size of 12 wildly tilted football fields, its 30-degree slope ending in a 7,000-foot drop to the Central Rongbuk Glacier below.

Yet here was the corpse, lying fully extended, face down, and pointing uphill. The head and upper torso were frozen into the rubble that had accumulated over the decades. The arms, powerfully muscular still, extended above the head to strong hands that gripped the mountainside, flexed fingertips dug deep into the gravel. The legs extended downhill, one broken, the other gently crossed over it.

"We weren't just looking at a body," says Hahn. "We were looking at an era, one we'd only known through books. The natural-fiber clothes, the fur-lined leather helmet, the kind of rope that was around him were all so eloquent. As we stood there, this mute but strangely peaceful body was giving us answers to questions that everyone had been asking for three-quarters of a century: the fact that a rope had been involved, that there was no oxygen apparatus."

The hobnailed boots, of course, was the giveaway. No climber had died at this altitude between 1924 and 1938, and hobnailed boots had given way to crampons by the eve of World War II. And if anyone had fallen, surely it would have been the inexperienced Irvine. But when Richards began gently separating the ragged clothing—several layers of cotton and silk underwear, a flannel shirt, woolen pullover and trousers, a canvaslike outer garment—he turned over a piece of shirt collar and revealed a fragment of laundry label: G. Leigh-Ma...

The climbers looked at one another dumbly. Finally someone said out loud what everyone else was thinking: "Why would Irvine be wearing Mallory's shirt?" But then they found another tag: G. Mallory. Then a third.

"Maybe it was the altitude and the fact that we'd all put aside our oxygen gear," says Hahn, "but it took a while for reality to sink in. Finally it hit us. We were in the presence of George Mallory himself."

"Now I realized why I had said it wasn't Irvine," Politz recalls. "It was the position of the body. The body we were looking for—a body long assumed to be Andrew Irvine—had been seen in 1975 by a Chinese climber, Wang Hongbao, during a short walk from his Camp VI tent at 26,980 feet. He described the body as gape-mouthed, its cheek pecked by goraks. But this body was face down. What's more, it was too far from the Chinese camp. No one in his right mind would have gone for a short walk where we found this body. I just sat down. My knees literally got weak. My jaw dropped. Next to me, Dave was going, 'Oh, my God, it's George. Oh, my God.' "