About the movie
In 1982, a very large alien spaceship stops above Johannesburg, South Africa. Reports suggest that the ship became stranded after a command module separated from the ship and dropped to Earth, nowhere to be found. After cutting their way inside, an exploratory team discovers a large group of unhealthy and leaderless arthropod-like species. These alien creatures, derogatorily referred to as prawns, are taken from the ship and housed in a government camp inside Johannesburg called District 9, which soon turns into a slum. In the first decade of the 21st century, Multinational United (MNU), a private military contractor, is placed in charge of policing and relocating the now 1.8 million aliens to District 10, a new camp 240 km (149 mi) northwest of Johannesburg.
Wikus van de Merwe is the MNU field operative assigned to lead the relocation, which begins with the serving of eviction notices on August 9, 2010. As the work continues, some nearby aliens are shown distilling a liquid from a piece of their technology into a small canister. In raiding one of the aliens' hovels, Wikus discovers the container, but accidentally sprays some of the liquid onto his own face. The other alien, named (by immigration authorities) Christopher Johnson, served his eviction notice by Wikus, questions the legality of the eviction and demands his rights. That night Wikus falls ill, is taken to hospital, where his left lower arm is revealed to have mutated into an alien appendage and he is overpowered and taken into MNU custody. Knowing Wikus' value as a human-prawn hybrid, MNU intends to vivisect Wikus before he fully transforms into an alien, in an attempt to replicate his ability to operate alien weapons, initially only operable by aliens. But, with his new strength, he overpowers his MNU captors and escapes.
Now a fugitive, Wikus takes refuge in District 9 and returns to Christopher's shack. Initially hostile towards Wikus, Christopher eventually reveals that the canister Wikus confiscated contains a liquid which would allow Christopher to activate the mothership and leave the planet. After Christopher reveals that the lost command module is hidden under his hut, he agrees to help reverse Wikus' genetic transformation if Wikus, in turn, retrieves the canister. Wikus agrees and tries to buy weapons from the local Nigerian gang. Their leader, the paralyzed warlord Obesandjo, seizes Wikus, seeking to gain his power to operate alien weapons, which he believes he will achieve by eating Wikus' mutated arm. Wikus again manages to escape taking some of the alien weapons Obesandjo possesses.
Wikus and Christopher break into the MNU offices using alien weapons and retrieve the canister. They then fight their way back to District 9, but Christopher, having witnessed evidence at the MNU labs that MNU is performing medical experiments on his race, informs Wikus that he has decided to return to his homeworld to seek help for his people before he cures Wikus, which would take three years. Frustrated, Wikus knocks Christopher unconscious and powers up the command module with the help of Christopher's son. However, soon after its takeoff, the spacecraft is shot down by MNU, causing it to crash nearby.
MNU forces take Wikus and Christopher prisoner, but Obesandjo's gang ambushes them as they attempt to leave District 9. The Nigerian gang captures Wikus and prepares to sever his mutated arm for Obesandjo. However, from the command module, Christopher's son activates the mothership as well as a mechanized battlesuit that kills Obesandjo and his men. Wikus then uses the suit to battle both the Nigerians and MNU's paramilitary. Wikus rescues Christopher from MNU mercenaries, allowing the alien to get to the command module. Promising Wikus that he will return to reverse his transformation, Christopher returns to the mothership. Heavily wounded and in a much more advanced state of his mutation, Wikus crawls out of the battlesuit and is confronted by Venter, the sole survivor and captain of the MNU squad. However, before he is able to kill Wikus, aliens in the camp dismember and eat Venter.
Christopher activates the mothership's engines, and Johannesburg's residents celebrate its departure. A series of interviews and news broadcasts are then shown, providing various opinions on the events. The aliens are successfully moved to District 10, said to have a population of 2.5 million and growing. MNU's illegal experiments on aliens are exposed, although the employee who exposes the operation is himself prosecuted. Some people theorize about Wikus' fate, while others hypothesize that Christopher Johnson might return for the refugees, or perhaps declare war on humanity. Wikus' wife reveals that, having found a small metal flower on her doorstep, she has hope that her husband is still alive. In a scrapyard, an alien with a bandaged left arm and human right eye crafts a flower out of metal.
