District 9 has a premise that can't be beat: After aliens descended on Johannesburg (the narration seems almost flattered that the aliens didn't choose Chicago, Washington or New York), they are cordoned off in a shanty town known as District 9. Vikus (Sharlto Copley), a corporate lackey assigned to the location, gets infected with alien DNA, which makes him a moving target for interests that seek to exploit alien biotechnology. This leads to actions and explosions that rival the most bombastic of summer releases and makes for District 9's fatal flaw. The plot's emphasis on action over ideas is a disservice to a premise ripe for allegory and imagination. Expertly handled though they are, the action sequences are what's memorable, and therefore not that memorable at all.