Warning: Heavy Spoilers! You should really go and watch the excellent movie first!
Bong Joon-ho’s 2013 film Snowpiercer must be read as an allegory. While it might be plausible for Earth to enter a new Ice Age because of geo-engineering gone awry (which was actually meant to combat global warming), there is just no logical explanation for why the remaining few humans would go around the planet on a train at breakneck speed instead of just parking it at a nice station—except for the fact that it makes a nice allegory: “The train is the world”, as voiced by our reluctant hero. The world is complete with the underclass at the tail, specialized production sections in the middle (a prison wagon, a garden wagon, an aquarium wagon, a school/propaganda wagon, a sushi-bar wagon, a sauna, etc.), and a self-absorbed elite towards the head.
Yet at the very front of the train is the (economic?) engine pulling the whole thing—the ultimate objective of our revolting party’s bloody struggle for freedom and/or control. After wagon for wagon has been taken, the remaining three revolutionaries finally arrive at the engine where the infamous dictator and designer of the train invites our protagonist to dinner and explains in a malthusian argument that this and all preceding revolutions were planned all along to periodically kill off the over-boarding population of the train. Furthermore, he offers that his job as the lonely head of the train is no easier than the workers struggle for survival at the tail and that ultimately all parts of society need to work together to form the functioning whole. Finally, as he’s an aging dictator, he wants our protagonist to take his place.
Understandably confused at first, our protagonist finally declines the offer of taking control at the front, and instead chooses freedom for everybody by helping the two other remaining revolutionaries (a girl and her father) to blow up a door at the side of the train. The explosion causes an avalanche, derailing and crushing the entire train and—literally—train-wrecking everything. It appears the only survivors crawling out under the wreck and stumbling innocently out into the endless snow are a young boy and the teenage revolutionary girl.
As eloquently expressed by Acid Cinema:
While movies like In Time or Elysium admit that the system is broken, they also offer reassurances that it can be fixed (in Elysium’s case with the laughably literal push of a button). Snowpiercer, on the other hand, argues that perhaps the system is broken beyond repair, that the only way to fix it would be to scrap everything and just start over.
While starting anew with a clean slate is appealing on an emotional level, personally I still prefer to believe that the system can be fixed without destroying everything.