... where they sold cat food to the aliens for exorbitant prices

Thirty years ago, aliens arrive on Earth. Not to conquer or give aid, but to find refuge from their dying planet. Separated from humans in a South African area called District 9, the aliens are managed by Multi-National United, which is unconcerned with the aliens' welfare but will do anything to master their advanced technology. When a company field agent contracts a mysterious virus that begins to alter his DNA, there is only one place he can hide: District 9.