Joe Simpson and Simon Yates set out to climb the west face of the Siula Grande in the Peruvian Andes. It was 1985 and the men were young, fit, skilled climbers. The west face, remote and treacherous, had not been climbed before. Following a successful 3-day ascent, disaster struck. Simpson fell a short distance and broke several bones in his leg. With no hope of rescue, the men decided to attempt descent together with Yates lowering Simpson 300 feet at a time in a slow, painful process that could have potentially been deadly for both. One further misstep led to Yates unknowingly lowering his injured partner over the lip of a crevasse. With the gradient having gone from steep to vertical, he was no longer able to hold on. Certain they were about to be pulled jointly to their deaths -- the only choice was to cut the rope.