Documentarian Macdonald turns to reenactments to provide a dramatic narrative for this saga of two British climbers whose adventure in the Peruvian Andes in 1985 goes horribly wrong. Simpson (Mackey) and Yates (Aaron), both in their early twenties, decide to test their abilities on the previously unclimbed west face of Siula Grande. They make it to the top but are beset by a storm during their descent when Simpson breaks his leg. Yates attempts to lower his partner down the mountain but Simpson goes into a crevasse. Uncertain if Simpson is still alive, Yates must then decide whether to cut the rope binding them together and make his way alone back to base camp or risk dying himself. How they both survive constitutes the rest of this harrowing story of survival. Simpson and Yates provide their own narration; based on the book by Simpson.