In a week when one third of British hospitals have been found not to meet even the most basic standards of hygiene and an investigation into the deaths of patients of the serial-killer GP Harold Shipman concluded that nearly three hundred of patients may have died in suspicious circumstances, the prospect of never getting ill certainly seems an attractive one. David Dunn (Bruce Willis) awakes to find that he's the only survivor of a train crash. Headlines proclaiming his sole-survivor status bring him to the attention of Elijah (Samuel L. Jackson) who has suffered all his life from a brittle bone disease resulting in numerous horrendous fractures - the other kids at school used to call him Mr Glass. He passed the long hours he was forced to spend ying in hospital beds reading comic books. Too many stories about men in tight costumes defeating evil has left him convinced that such "superheroes" do exist and he confronts David Dunn with the possibility that he just might be one.

The central gag of this film is that it shows how these extraordinary events are experienced by a very ordinary dysfunctional family - we see Dunn in the first few frames of the film slipping off his wedding ring as a cute woman sits down next to him on the doomed train, his estrangement from his wife is superbly evoked in the awkwardness of their body language as they embrace at the hospital. This dysfunction climaxes in his son's attempt to shoot him in order to prove that he's a super hero - "I'll just shoot him once." For this weird scene alone the film's probably worth seeing, especially if you ever had any doubts about the wisdom of strict gun control.

Such a pity then that the rest of it is either hackneyed or just plain incoherent. Samuel L. Jackson struggles gamely to explain what the hell comic books have to do with anything and why we should regard them as "art" (something to do with the baddies having bigger heads), but even he doesn't manage to deliver lines claiming a kinship between Captain America and ancient Egyptian hieroglyphs with much conviction. And how much of a twist is it (I won't give away the details) to have the crippled black guy turn out to be the baddie? Wouldn't it have confounded expectations even more if he'd turned out to be the good guy?

I think what Samuel L. Jackson (or rather Elijah) is trying to say is that comic books are one of the modern-day repositories of myth (Hollywood movies of course being another). "Unbreakable" cleverly shows how the heroes of these myths might actually come to walk among us. And indeed we may well see, the next time some poor soul is the sole survivor of a disaster that the idea of a natural, "unbreakable" superhero has itself re-entered into the popular mythology that headline writers, comic book artists and film-makers both nourish and feed upon.