Taking away robots and aliens and high tech stuff, science fiction is first and foremost a way to shine a light on social issues that we face today. Good science fiction has the power to stay thematically resonant, no matter when you watch it. When District 9 came out, it was about apartheid, racism, and class issues. Watching it in 2016, however, it's impossible not to see it as a reflection of the current refugee crisis.
District 9 takes place in a version of Earth where a spaceship full of aliens become stranded just above Johannesburg, South Africa. With no way to return home, the aliens must be integrated into human society. Only they're different. Misunderstood. Feared. So it doesn't take long before they're rounded up and placed in ghettos that isolate them from the rest of society.
Quite a coincidence that the spaceship is hovering directly above Johannesburg, giving the aliens the opportunity to become second class citizens in a city that has historically had more than its fair share of segregation.
The film throws us into this storyline twenty years after the aliens first landed, so the humans have had plenty of time to develop prejudice and hatred towards their prawnlike visitors. Our protagonist is a nebbish-looking office drone named Wikus, who is tasked with going to the District 9 ghetto and convincing the aliens to sign up for a new camp. We never see the new accommodations for the aliens, but it's strongly hinted that it's a similar transition as going from, say, the Warsaw ghetto of World War II to a Nazi concentration camp.
While Wikus is slyly violating the rights of the aliens, he accidentally gets a face full of alien gunk, and that's where all of his troubles begin. Wikus is about to have a terrible horrible no good very bad day.
The liquid that was in this tube had been collected by the alien Christopher Johnson, which he and his ridiculously adorable prawn son were going to use to fly back to their planet. Unfortunately for Wikus, the side effect of this miracle juice is that it also happens to turn humans into prawns, which is like the exact opposite of what you want.
This movie somehow manages to contain every single body horror nightmare you've ever had. As medically dubious as the idea of a human turning into an alien may be, credit to the film, they have created a disgustingly realistic depiction of the metamorphosis. Including a charming scene where Wikus is eating cat food and a bunch of his human teeth start to fall out. Delicious.
And ok, so this might be really shallow of me, but I kind of love the dude makeover that Wikus gets after the alien infection. Yeah, he only stays that way for a day or two before turning into a prawn, and he spends most of that time being tortured and hunted by the government, but still...I'm into it.
Of course, now that Wikus is starting to look like a crawdad, he suddenly realizes how awful it is to treat the aliens the way that they have. To be fair to Wikus, though, he was a low level cog in the machine, and had no way of knowing the truly disgusting experiments that were being conducted on the aliens. His eyes opened (and sort of turning vaguely reptilian), he has no choice but to work with Christopher Johnson and help the aliens escape -- it's the only way he can turn into a human. (Although maybe I'm just being pessimistic, but Wikus, I just watched all of the skin on your hand and arm fall off. I really don't think the aliens have a magic wand that will grow that back. Sorry.)
Ultimately, it's almost impossible to walk away from this movie not feeling grossed out by humanity. It doesn't matter how advanced, educated, cultured, or valuable a people are, when they are put in a desperately helpless situation, they are doomed to be subjugated or rejected unless their rescuers make a choice to show them humanity. Unfortunately, that's out of the wheelhouse of most modern societies.
People en masse are fearful and suspicious, willing to be cruel to protect themselves against a perceived threat. And as we have seen from our current batch of presidential candidates (I'm not going to name any names, but I'm thinking specifically of the Oompa Loompa-looking son of a bitch with tiny hands, a hyper-inflated sense of self-worth, and the vocabulary of a third grader), politicians are not above playing into these fears if it benefits them. Are Muslims really a threat to the everyday American? I mean, unless they own a summer cottage in Damascus, the answer is so absurdly obvious that it's pretty offensive to ever ask it.
So...yeah. Happy endings, y'all.