Review: 127 Hours (15)*****

What none of them can realise is that the next 127 hours will become the defining episode of Aron Ralston's life. For when man takes on nature and the wild, man will always lose.

Except, of course, that Ralston won – in a fashion. Trapped in a narrow gully by a half-tonne boulder that pinned his hand to the rock face, he eventually took the only path open to him: he cut off his own right arm with his penknife...

Ralston's story has passed into American legend. Yet director Danny Boyle and co-writer Simon Beaufoy, the successful team behind Slumdog Millionaire, show the hubris and downright stupidity of Ralston as he discovers to his cost that he is no 21st-century Superman.

In what becomes a one-man show la Tom Hanks in Cast Away, Boyle, Beaufoy and James Franco (playing the unfortunate back-packer) present Ralston as a driven individual determined to wriggle out of his predicament.

Systematically he goes through his bag to see what he has got. He begins a video diary of his experiences. He starts to chip away at the boulder keeping him prisoner. "Don't lose it," he tells himself. "Do not lose it."

Boyle plays around with split screen, video footage and music. He scatters the film with hallucinatory images as Aron's water begins to run out. When a massive storm floods the crevice he stocks up, but knows he must escape or die. "This rock has been waiting for me its entire life," he muses.

At the core of the film are two aspects: a stand-out performance from Franco as the arrogant super-athlete who realises too late the error of his ways, and The Moment of Truth when Ralston must first break, and then sever, his arm in a bid for survival.

Said Moment requires steely determination from Ralston and from watching viewers. It's a gory piece of DIY butchery that had preview audiences fainting. And so they might.

An unusual film that might have been just another slice of slap-on-the-back Hollywood hoopla, 127 Hours emerges as a cautionary tale of what not to do. Take on nature at your peril. Offer it two fingers and it will respond. Aron Ralston realised that too late and gave his right arm in the process. The Boyle/Beaufoy approach is to paint that portrait warts and all. Theirs is a stronger film because of it.