The young man's right hand was trapped under a falling boulder, so he couldn't move. He became progressively more exhausted and dehydrated over several days, and eventually cut his own hand off with a blunt knife, and then walked out of the wilderness. It's a story that would be hard to accept in fiction, except it is real.
There is a genre of minimalist survival-stories. I think my favourite is Touching the Void. I watched Buried last November, about a contractor stuck in a grave in Iraq, which was too spare to be quite successful. This one is very much Danny Boyle's take, and I like his style. It's vivid and visceral, there are echoes of Sunshine and Train Spotting, and I think it presented a story which could have been exploitative, and managed to make you feel the person's terrible situation without being creepy. It was quite sentimental, but then I think people are sentimental in real life.
For most of the film the drama is internal, but unlike Buried, the experience is dramatised so there is a lot going on, on screen. It is minimalist in its conception - one man between two walls of rock - but visually there is a lot of action, special effects, other people and so on. The hiker made a video diary in real life during his experience. The guy very understandably has not given permission for the real thing to be broadcast but it is reproduced (reimagined perhaps) here.
It's gruesome and bloody in places, and I think this is the major factor to take into account when you decide if you want to see it. It made me think about will and survival. It made me think about giving birth. When I gave birth things didn't go so well (they accidentally severed a small artery) and there was a lot of blood, and internal organs being pulled out through a gap in my tummy and so on, and there comes a point when you just think- I must go onwards through this, there is no back out, just forward. Also I think it gives you a contact with that silent place inside yourself that is rational and unmoved. This film made me recall those feelings.