Deceptive-advertising alert. "District 9" is positioned in ads and trailers as violent, thrill-a-minute B-movie science fiction in which Earth-stranded aliens fight heavily armed security forces. And it is that. First-time writer/director Neill Blomkamp spatters the screen with blood, explosions and disintegrating bodies. On that level, it knocks "Transformers" for a loop.

But socked in with the whiplash action and over-the-top gore is a story that's shockingly funny, clever and emotionally resonant. "District 9" is that rarest kind of film, magnificent trash.

Blomkamp immerses us in a meticulously detailed world where thrills, performance and story work in seamless harmony. Of all the various sci-fi dystopias -- societies that have gone mad -- "District 9's" is the most believable: present-day Johannesburg, South Africa. The film, shot like a fly-on-the-wall documentary, paints a harsh picture of the city. Riddled with crime, violence and unemployment, it's now stressed by an influx of immigrants.

We get the background on the newcomers from talking heads and news footage. For 20 years a huge spaceship has hovered silently over the city, immobilized and out of fuel. Inside were tens of thousands of diseased, malnourished aliens.

The aliens -- crustaceans disparagingly called "prawns" -- are intelligent. They have a language that humans can understand, and technology that humans haven't mastered. But they have degenerated in captivity. They now live in a vast ghetto patrolled by mercenaries. They are filthy, they breed like cockroaches, they are violent when provoked, and the city is plastered with no-trespassing "Humans Only" signs. In their concentrated poverty, the refugees suck up benefits that could go to needy humans. Everyone resents the prawns. At least they provide employment for petty bureaucrats like Wikus (it rhymes with weakness) Van De Merwe.

Wikus is a functionary at the corporation that runs the alien ghetto, a job that suits him perfectly. He's an obnoxious back-slapper who, thanks to his influential father-in-law, is charged with relocating the prawns from their shantytown to a distant prison camp. A typical film would make an idealistic scientist or daring soldier our guide into the alien's world. "District 9," which boldly undercuts conventions at every turn, positions Wikus, the small-time careerist, as our antihero.

He leads a SWAT team carrying eviction notices; the totalitarian love for documentation requires every alien to make its "scrawl" on the dotted line. Behind one door, Wikus and his crew find a hive of alien embryos, which they torch. "Hear those eggs popping? Just like popcorn," he blurts with glee. He's a poster boy for the banality of evil. But unlike the South African security thugs and African gangsters who shoot prawns at will, he's redeemable.

Newcomer Sharlto Copley is stunning in his first film role, delivering a performance the equal of De Niro in his prime. Copley gives Wikus a pathos that somehow makes you pity him despite everything. You look at Wikus and recognize the worst parts of yourself. Any good drama requires its protagonist to travel an arc of growth that results in a changed worldview. What happens to Wikus transforms him from a rank specimen of inhumanity into a tragic character, and ultimately a hero. Copley hits every note perfectly.

"District 9" is a compelling apartheid allegory -- think "Aliens" meets "Schindler's List" -- but there's not a moment of preaching in it. This is first and foremost an electrifying ride. The effects are jaw-dropping and sometimes hilarious; there's nothing like seeing a soldier taken out by a flying pig. Not only are the interactions between aliens and humans entirely convincing, but the computer-generated prawns can act! The story repeatedly hints that there may be a sequel, and I'll be at the head of the line for tickets. "District 9" is the dawn of the next big genre thing.

Colin Covert • 612-673-7186