On July 17, 2005, as a freakish heat wave bore down on Pakistan's western Himalayas, the 26,660-foot peak Nanga Parbat gave up its dead, laying them out on thawing patches of the Diamir Glacier, a huge expanse of shifting ice more than 12,000 feet below the summit. Over the decades, the glacier had become a catchall graveyard for at least a dozen climbers who'd died on the Diamir Face, the treacherous western wall of the world's ninth-tallest mountain.

The first of two partially intact corpses showed up early that day, when Pakistani guides and Spanish climbers on the 12-square-mile glacier came across a broken, desiccated body. The leg bones were wrapped in brightly colored wind pants; on one skeletal foot was a sun-bleached Koflach plastic boot. Judging by the clothing's vintage, the guides guessed the body was that of a Korean expeditioner lost in 1993.

Later, three Pakistani guides from the nearby village of Bunar Das made another grim find: a headless corpse, consisting of a rib cage, a strip of spine, shoulder bones, tufts of hair, and scraps of clothing. The remains were scattered amid gray glacial rubble, near the foot of a dirt-streaked ice cliff running with meltwater. At first the guides—Abdul Mateen, Faz al-Haq, and Abdul Manan—thought the body could have belonged to any number of men lost on the western flank in recent years. But when the talus yielded a leather boot entombing a wool-socked foot, they knew they'd probably stumbled across an older tragedy, since plastic footwear had replaced leather after 1980.

This, they realized, could be the body of Günther Messner.

Günther, the younger brother of Reinhold Messner—the 61-year-old Tyrolean climber widely considered history's greatest mountaineer—was by far the most famous MIA on Nanga Parbat, and, a few years back, Reinhold had specifically asked the Pakistani guides to search for him. Günther, 24, had gone missing in June 1970, when he and Reinhold—then 25—made a daring first ascent on the south flank of the peak via the 14,763-foot Rupal Face, one of the tallest alpine walls on earth.

The feat was a stunning success for two young climbers on their first Himalayan expedition, but only Reinhold lived to tell about it. As he described the tragedy later, Günther was stricken with altitude sickness soon after they summited, on June 27, and was too debilitated to backtrack down the sheer ascent route, particularly since they had no rope. After a sub-zero bivouac, followed the next day by a much debated episode in which Reinhold shouted to other climbers at a distance but somehow didn't or couldn't convey Günther's plight, the brothers apparently decided that their only chance of survival was to pick their way down the unfamiliar but less steep Diamir Face. If they succeeded, they would score another coup in the process: the first complete traverse of Nanga Parbat.

According to Reinhold, near the end of the descent he'd pushed an hour or so ahead of his brother, believing the worst was behind them. Then, out of view—in an area toward the bottom of the Diamir Face—Günther disappeared in what Reinhold assumed was an avalanche. He could find no trace of Günther. Grief-stricken, Reinhold staggered on for the next two days before finally making it to safety in the Diamir Valley.

In the aftermath, the damage to Reinhold's body and soul was immense. He lost seven toes and several fingertips to frostbite. Worse, he'd lost his beloved brother and the climbing partner he once called his life's "accomplice."

"Günther!" he'd shouted endlessly as he searched for him on Nanga Parbat. "It was the anguished cry of a lost animal," he wrote later. "I had suffered. I was badly frostbitten. I had died."