*it is 20 years after the alien ship arrived and stopped over Johannesburg, ever since it has been floating there, the aliens inside them called prawns were moved into a large encampment that eventually became a slum,

*The prawns are not allowed out of district 9, you are an officer with the alien affairs who has been sent into district 9 to evict the prawns, and investigate if any of them are criminals, however when you go to one of the prawns shacks you find something interesting.