Meet Wikus van der Merwe. He's a pen-pushing middle manager who looks and sounds like an apartheid-era Post Office employee. He's into arts and crafts and making trinkets for his wife. He's not exactly your average hero.

But 'District 9' isn't exactly average either. A sci-fi action story set in a Jozi squatter camp, featuring aliens that look like human-sized shrimp, starring a guy who's never acted before, and directed by a South African, it has all the makings of 'Killer Piranha Zombie Mutants 4' or some of that other B-grade schlock the Americans make here on the cheap.

If that's what you're after, go rent 'FrankenShark 5: The Taste of Fresh Blood'. Subverting a premise as battered as your average minibus taxi ? aliens come to earth ? Neill Blomkamp's brutally thrilling film takes a panga, or some other sort of traditional weapon, to conventions and expectations.

Perfecting the ragged handheld documentary style introduced by 'The Blair Witch Project' and refined by 'Cloverfield', it combines on-the-ground footage with news reports and talking head interviews to create an alternate Johannesburg that seems staggeringly real.

That authenticity is only reinforced by the treatment of the aliens themselves. Refugees now living in shacks outside Johannesburg, the "Prawns" are introduced so early and matter-of-factly you just have to believe. None one of that building anticipation nonsense with them finally revealed as unintentionally laughable CG blobs.

These ETs are right here, right now. And Wikus, as the official in charge of the operation to move them to another settlement, is thrown right into their midst. Our guide in this unsettling, but oddly familiar, parallel world of oppression, segregation and prejudice, he's the single most important element of Blomkamp's film ? and, despite the presence of extra terrestrials, its most unlikely.

With his big moustache, R20 haircut and Naas Botha accent, the office drone initially does little more than elicit chuckles of recognition. The potential for caricature is huge but Sharlto Copely isn't playing for laughs. As the visceral story descends into darkness, his transformation from meek simpleton is more than physical, the first-time actor a torment of despair and fear.

Sympathy for him is easy, but like a real person, his true motives remain questionable, some of his actions deplorable. As so much else about 'District 9' this is no black and white issue. After all, beneath its adrenalised shootouts, spaceships, helicopter gunships, weapons of mass destruction and SANDF-issue Caspers, linger issues of apartheid and xenophobia ? as well as laugh out loud satire and physical comedy.

Like the country where it is based, 'District 9' is a mass of contradictions ? yet intelligent, thought-provoking, and action-packed, it is anything but a local cliche.