“Everybody thinks that coming down is the easy bit. It makes sense, but don't believe it for one minute.” -Walter Bonatti

Although he didn't summit K2 — nicknamed “Savage Mountain” for being the world’s second tallest peak — Bonatti knew how unforgiving it was. On Aug. 1, 2008, 25 expert climbers would learn how much truth there was in Bonatti’s words. In less than 48 hours, 11 would die. The disaster was one of the deadliest incidents in mountaineering history. Yet, what actually happened on the mountain is still shrouded in mystery to this day.

Director Nick Ryan’s documentary, The Summit, uses a blend of documentary and archival footage, survivor interviews, and reenactments in order to bring forth what really happened — a truth that became lost in the plethora of rumor- and assumption-driven media throughout the Internet. It focuses on many stories, but pays special attention to the controversy that surrounded the death of Gerard “Ger” McDonnell, the first Irishman to ever summit K2.

The Summit is both immersive and powerful. As one of the first climbers slips helplessly to his death, it takes a moment to realize that the reenacted scene actually happened, and then, the gravity of the climbers’ situation takes hold. It puts the viewer in the middle of the confusion, fright, pain, and moral dilemmas that the climbers felt. But still, it only grazes the reality.

'What Kind of Mentality Does It Take, To Take On Worse Odds Than Russian Roulette?'

“It started to become clear to us that something had happened on the mountain that was quite extraordinary, and truly tragic because of the nature of it,” Ryan told Medical Daily.

For every four people that stand at the summit of K2 (28,251 feet, or 8,611 meters), one person dies trying. “What kind of mentality does it take, to take [on] worse odds than Russian roulette,” said Ryan. Even its safest climbing route, known as the Abruzzi Spur, is fraught with physically challenging and exhausting obstacles. Add the possibility of hypoxia — lack of oxygen, which leads to altitude sickness and feelings of apathy — dehydration, impending frostbite, and harsh weather, and it becomes as much a physical challenge as it is a mental challenge.

“I think that this is a big point … It’s not all about whether you can tie a knot or put your crampons on correctly, it’s about — can you rig a rappel when you’re terribly dehydrated, hypoxic, and fuzzy headed — skills and decision making need to be almost second nature,” Luanne Freer, M.D., founder and director of Everest ER, told Medical Daily.

Entering the 'Death Zone'

Although these challenges became more difficult as the climbers trekked higher, it was after they entered the “death zone” at 8,000 meters that they faced the most difficulty. At these altitudes, the air is so thin that it’s almost impossible to sustain life. “Basically, the oxygen doesn’t get into your extremities, so your body starts to shut down,” said Ryan. “Then your organs try to compensate, so they expand, and start to liquefy.” Because of this, the climbers carried supplemental oxygen tanks as they climbed toward the summit.

At 8,200 meters, the mountain’s most dangerous obstacle, known as the bottleneck, is a rock-lined pathway directly underneath a giant, overhanging ice shelf, known as a serac. It spans hundreds of meters in height and width, and forces climbers to climb up underneath it, sometimes completely vertically. It can break at any moment, sending an avalanche of ice plowing down on the climbers. Climbing the bottleneck can take several hours on its own, and the climbers still aren’t safe. Once climbers reach its base, they still have to traverse along it horizontally, slightly around the mountain, and up, at about a 60-degree slope, for another few hours. Only then have they passed the serac’s threat.

Within 48 hours, the 18 climbers that were able to climb past the serac would see, firsthand, how dangerous it could be upon their descent. It broke four separate times. And with each break, ice “the size of cars and fridges” fell, sweeping climbers with it. The events that transpired during these avalanches have been mired in controversy. Did the climbers try to help one another? Or did they all fend solely for themselves?

Unraveling K2's Mystery

Ryan looked to Pemba Gyalje Sherpa, a hero on the mountain and member of the Norit K2 team, for answers. Altitude sickness (they had run out of oxygen), and physical and mental exhaustion would lead many to have foggy memories, but Pemba’s head was surprisingly clear. “On K2 I was very lucky because my [mental] condition was perfect,” he told Medical Daily.

“There’s a distinct lack of ego in the Sherpa, but also, when I got to see the footage a year later, everything that he said; his description of the base camp meetings, what people had said, the agreements that were made… was almost verbatim. So there was a sense that his memory was intact,” said Ryan.

Pemba’s memory held many of the story’s missing pieces. But as the film’s events unfold, and the interviews, reenactments, and footage come together to form what really is (still) a puzzle, you begin to realize that, as Ryan said, “we can sit here and we can speculate all we like about what happened on the mountain that day; what they did, and we can say ‘he did this or he didn’t do that,’ but if you weren’t there, you don’t know. Only the mountain knows.”

The Summit will be released in select theaters across the country on Oct. 4.