The film is set in the future (AD 2031) where, after a failed experiment to stop global warming, an ice age kills off nearly all life on the planet. All that remains of humanity are the inhabitants of the Snowpiercer, a train that travels around the globe and is powered by a sacred perpetual-motion engine. Its inhabitants are divided by class, but a revolution is brewing. The lower-class passengers in the train's tail section stage an uprising, moving car by car toward the front of the train, where the train's creator and absolute authority resides in splendor.