Joe Simpson and his climbing partner, Simon Yates, undertook a climb in the Peruvian Andes in 1985. The two young and ambitious mountaineers set off to scale the hitherto unclimbed west face of Siula Grande, a remote and treacherous 21,000ft peak. Starting the descent through a blizzard, Simpson fell, shattering his leg. An heroic battle for survival unfolded in which both men were faced with life or death decisions which test the human spirit to its limit.