We all know that fast food is bad for us. It's already been covered in books, films, television - in fact, even if you haven't seen or heard anything, it's blindingly obvious that a big greasy burger is not going to produce healthy results. So what is there left to say?

Richard Linklater (who brought us last year's A Scanner Darkly) has teamed up with Eric Schlosser, the writer of factual novel 'Fast Food Nation', to create a fictional fast food chain (Mickey's Burgers) and a ensemble of fictional characters. And they used them all to say a lot more than just 'burgers are bad'.

Not that they come down on the side of burgers. One third of the film follows Don (Greg Kinnear, Little Miss Sunshine), a marketing exec at Mickey's sent to investigate why traces of cow poo have been found in their burgers. Yummy.

The film's other narrative strands follow a group of illegal Mexican immigrants sent to work in a meat-packing factory (the poo source), and a bunch of teenagers who work in one of the chains. Their work ethics are interesting to ponder, but the biggest point is summed up in one scene, when a group of activists break down a fence up at the burgers-to-be cattle ranch in order to save the animals. The fence is down, but the cows just don't want to move - they're either too dumb to realise, or too afraid to escape their surroundings.

It's Linklater's attack at apathy - his annoyance at people putting up with the various wrongs in the world because they're too lazy, or afraid, or stupid to really do anything about it, even when there's sometimes a solution staring them in the face.

At times the tone tips a little too far into preachy, and the split narrative creates a strange, disjointed feel to the piece. But with a great cast, some strong messages and a clever way of transferring the text to screen, Fast Food Nation definitely provides something meaty to chew on - though after seeing it you might feel like avoiding meat for a while.