“Snowpiercer” shouldn’t work. Based on French comic book “Le Transperceneige,” this movie’s core concept should derail, but a tense and gripping story make up for the wildly implausible setting.

In the movie’s timeline, an attempt to halt global warming made the Earth too cold to sustain human life. The few remaining people all live on a giant train that endlessly circles the globe. Within the first ten minutes, “Snowpiercer” raises questions such as “why a train?” and “wouldn’t a giant fortress be easier to maintain, use less locomotive power, and be safer if the weather gets rough?” Hell, just one tiny problem with the track could spell the end for everybody.

Luckily, nothing like that ever happens over the course of seventeen years. When “Snowpiercer” starts, a class system has arisen within the train. Chris Evans’ character Curtis lives in the tail. This area serves as society’s basement, while an upper class living in train cars closer to the train’s deified engine live in luxury.

The audience is immediately drawn to Curtis’ side when it becomes clear just how hellish his part of the train is. The people are frequently abused at the hands of the soldiers.

Class tensions come to a boiling point, and Curtis leads his fellow tail-enders in an attempt to seize control of the train. They fight the hierarchy one car at a time.  

Some skillful direction from Bong Joon-Ho, director of South Korean monster movie “The Host,” allows some potent dramatic moments to rise above the limits imposed by the story’s ridiculous setting.

Accompanying the drama is plenty of action in the form of close-quarters fighting that is both thrilling and uncomfortably vicious.

Forced into a linear progression where each train car feels like an isolated videogame level, “Snowpiercer” actually manages to avoid being completely predictable. The cars contain plenty of different environments including a classroom, a garden, a dance club and an aquarium, as well a number of different threats. The action makes audiences’ pulses pound every time Curtis’ engineer ally Namgoong Minsu, played by Song Kang-ho, prepares to open the door to the next section.  

As Curtis’ revolution works its way up the train, more unbelievable plot points surface and become especially prevalent around the movie’s climax. Specifying them here would spoil the movie, but you should know you haven’t seen such colossal gaps in logic since “Pacific Rim.”

Luckily, the tale of rebellion and class conflict at the heart of “Snowpiercer” is compelling enough to deliver plenty of thrills and emotional power despite the flaws. Though the social commentary is a bit heavy-handed, “Snowpiercer” is a competent action movie that viewers shouldn’t have any trouble getting emotionally invested in.