Una raza extraterrestre obligada a vivir en barrios marginales en la Tierra, de repente encuentra a un espíritu afín en un agente del gobierno que es expuesto a su biotecnología. Los hechos sucederán en Sudáfrica.

In 1990, a massive star ship bearing a bedraggled alien population, nicknamed "The Prawns," appeared over Johannesburg, South Africa. Twenty years later, the initial welcome by the human population has faded. The refugee camp where the aliens were located has deteriorated into a militarized ghetto called District 9, where they are confined and exploited in squalor. In 2010, the munitions corporation, Multi-National United, is contracted to forcibly evict the population with operative Wikus van der Merwe in charge. In this operation, Wikus is exposed to a strange alien chemical and must rely on the help of his only two new 'Prawn' friends.