I Am Legend sets up an interesting plot-line. We're in a futuristic New York where the search for a medical cure for one of the world's diseases has led to a virulent outbreak of a virus that has killed everybody (Emma Thompson is responsible, a scientist who thought she'd found a major cure which in fact becomes a killer itself).

When I say everybody, in fact there's one man Robert Neville who's not caught the disease (Will Smith) and he leads an eerie life in a capital city brought to a halt by the disease and now years later, grass grows on the main highways and wild animals inhabit the back streets.

Neville's a busy man. He works out (cue drooling from half the audience at the Will Smith six-pack), he's looking at downloaded TV news from the good old days, he's feeding himself and the dog, and he's down in his basement carrying out major lab experiments on rats trying to find a cure from this deadly virus.

He also goes out every day, avoiding the wild dogs and occasional vampire on the streets, to make sound waves broadcasts hoping for a reply from a sane person - his only other company is his pet dog Sam (cue many scenes where man chats lovingly to his pet mutt) and just when you think he really is all alone, of course he's not, there's a sane girl in the city (Alice Braga) and of course there's the pale and wild mutants who look like the've stumbled off the set of 28 Years Later. They inhabit the second half of the movie and yes the blockbuster really does verge from fairly sensible survivor set-up in the first half to tired unoriginal race-against-time thriller fighting off wild zombies in the second.

What's fairly clear here is that the writers had a good idea, but no real notion of how to end it, thus a film that sets up a reasonable storyline leaves itself open to derision as authenticity heads out the window.

It's a pity, but I expect the film will do good box office, as it has done in the States, on the back of Will Smith, a mysteriously engaging trailer, and audiences grateful to find another option away from irritating family and the manic Christmas sales.