Joe Simpson and his friend Simon Yates attempt to climb the western face of a mountain in Peru. As you may guess the climb doesn't go as smoothly as they would have liked, and facing the results of a terrible accident the pair are forced to make tough choices in order to survive. The story involves an amazing show of human endurance, and just what length people can go to in order to survive. Even in the harshest of environments.
The filming is fantastic. It mixes footage of the pair on the mountain, with interviews. All of it narrated by the people involved, and not by a third person. This was a fantastic technique I thought, which really allowed you to connect with the people.
It's one of my long time favourite films. There is also a book about it, which goes into greater detail than the movie does. It's a great watch/read, and I'd reccomend people check it out.