The stock response mountain climbers give when asked, “Why do you do it?” is simply, “Because it was there.” But that answer neglects the satisfaction they get from overcoming the greatest obstacles, the exhilaration of defying death as they push themselves up cliffs and hang over 1,000-foot drops. On one such perilous ascent in 1985, climbers Joe Simpson and Simon Yates discovered why the fear of death is completely justified.

Touching the Void recounts their trek up a previously unclimbed face of Siula Grande, a snow-covered peak in the Peruvian Andes of more than 20,000 feet. Simpson, Yates and hiking companion Richard Hawking tell the story of reaching the summit over ice cornices, sheer cliffs or through rock and snow while their fuel and water was running out.

During the descent Simpson broke his leg, and as Yates tried lowering him down the face, Simpson fell off a ledge and into a seemingly bottomless crevasse. He managed to survive and limped toward base camp, clinging to the hope that his mates hadn’t already packed it in.

Academy Award-winning documentary director Kevin Macdonald (One Day in September) adapts Simpson’s best-selling book of the same title for the screen. Void’s docudrama style uses firsthand accounts and documentary-style on-camera narration, but it also features a dramatic reenactment of the climb. Young climbers Nicholas Aaron and Brendan Mackey step into the cleats of Simpson and Yates as Macdonald’s camera follows them into the Andean heights.

While the original climb has yet to be duplicated, it is convincingly recreated on the cliffs and powder slopes used for the reenactment. A very real, human drama drives Touching the Void as it’s told by the people who lived it. Yates confronts a life or death decision on the mountain: Should he go down with his friend or cut the rope and hope that at least one can make it back alive?

He revisits his decision in the retelling, still questioning whether he made the right call and second-guessing his failure to look for his buddy the next morning, stranding him on the mountain.

Simpson’s story is one of human will. Left for dead, with no water and a broken leg, he pulls himself out of the crevasse, crawls over the glaciers and drops himself rock over rock toward camp. Each step and fall sends a jolt of pain up his leg, and the ever-present snow does nothing to quench his thirst.

Because Simpson himself tells the story, the film avoids any contrivances that would try to build suspense over whether he’ll make it. Instead, Void rides on the strength of Simpson’s quest for survival, a tale that has become climbing legend.

Set against the awesome heights of the Andes, the footage in Touching the Void is a spectacular backdrop for a very personal tale. Simpson’s pride corresponds with the enormity of the obstacle he overcame to preserve his own life in the shadows of the towering Siula Grande.