In 1990, a huge spaceship appeared in the sky above the earth, and people were panic-stricken, but also extremely curious. After a period of tense waiting, the alien spaceship remained silent. Humans finally approached it cautiously and forced their way into the cabin, only to find countless aliens. They were described as ugly, like shrimps, and in extremely poor health and weak. It turned out that this was a group of refugees from aliens. They were eventually accepted by the earthlings and lived in isolation in an area of Johannesburg, South Africa, which was called "District 9". After 20 years of reproduction, the number of alien refugees expanded to as many as 1.8 million, and conflicts with the surrounding humans continued. More and more humans called for the "prawns" to be driven out of the earth. After consultation, MNU (United Nations Organization) decided to relocate the alien refugees to a more remote area. Wikus (Sharlto Copley), an agent of the MNU Alien Affairs Department, was responsible for the relocation work. Wikus was arrogant and casual during the mobilization process, and frequently clashed with local residents. In the end, he paid the price for his actions. He was infected by the alien's mysterious fluid and Wikus slowly turned into an alien...