127 Hours (15)

Starring: James Franco, Kate Mara, Amber Tamblyn, Treat Williams

Consider yourselves warned: there will be blood. Danny Boyle's minimalist survival yarn has at its centre an act of almost inconceivable self-mutilation, yet its gruesomeness resides not so much in what we can see as the level of pain we are obliged to imagine. Just thinking about it makes you go... meeyaargh.

Is there anyone who still doesn't know what happened to Aron Ralston in the Utah desert one day in April 2003? If there is, here goes: this 28-year-old adrenaline junkie was out hiking in the wilderness without having told anyone where he was going.

While trying to negotiate a tricky crevice he slipped and fell, trapping his right forearm immovably between a boulder and the canyon wall. His predicament is fiendishly simple. He cannot cry for help, because there's no one around for miles. He has for company a videocam, a bottle of water and a small Swiss Army knife. What is he to do? And what is the film to do, with Danny Boyle, the most kinetic of modern directors, having chosen to lock his story in chronic isolation? Somehow he finds a way to pass the time, recreating the ordeal (from Ralston's own memoir, Between a Rock and a Hard Place) as a kaleidoscopic blur of hallucinations, reveries, flashbacks, or, as the poet had it, "fears, havings-to, faces". Shots of curving sunlight, or of a raven passing overhead, interrupt the lonesome vigil.

James Franco does his darnedest to resolve a performative conundrum: how to play a static action hero. It's not quite a one-man show – the early scenes involve Ralston frolicking with a couple of women backpackers – but for the most part it's just the camera on his face. Amazingly, he keeps his head amid the darkness of the canyon, and by that serene refusal to panic braces us for what we know will be coming. His fate, a dot in the distance at first, gradually looms into view. He has already drunk his own pee; now he must prove his mettle before dehydration and starvation undo him completely.

The cumulative intensity of this is never boring, but it is not quite enlivening, either. One never feels the horrific absurdity, for instance, of Ryan Reynolds trapped in a coffin in Buried, another film that dares to telescope isolation into an hour and a half.

The film posits an existential teaser – what would you have done in his place? – but doesn't deliver the smack of appalled satisfaction we should feel at its denouement.