In the near future, a chemical is sprayed into the atmosphere to reverse global warming. The problem is that it works too well and causes planet Earth to freeze. The last remaining humans are on a specially built train with an engine that can last forever. The train is designed to be a lifeboat forever moving. Years after the big freeze, the people in the back of the train are tired of their crappy existence, which is pretty terrible compared to their oppressors who live at the front, so they decide to revolt. They fight their way to the front while encountering strange new sights with each new car they pass.
The end of this movie has a lot to say about humanity, and most of it is not very good. There is the obvious environmental message, along with messages about class warfare and how humans will always fight each other no matter what the situation is.
This is a Korean made film, although 80% of the movie is in English. It is based upon a graphic novel.
Most of the movie is pretty interesting, although the violence is sometimes intense.