Joon-ho Bong’s first English-language movie, Snowpiercer, asks us to accept a ridiculous premise: that the only survivors of a planet-wide ice-age are trapped inside a high-speed train forever circling the earth.

Thankfully, the director doesn’t waste time philosophizing or establishing a complex futuristic world; all we know is the train and the lethal cold outside it.Chris Evans (worlds better than he’s been before) leads a rebellion among the lower-class passengers who want to break free from imprisonment. As his army fights to take control over their oppressors (the delightfully batty Tilda Swinton, for one), I felt like a kid in a magic shop: what awaits us behind the next door?

American action and sci-fi flicks don’t focus this much on class. Funny enough, the passenger list is so small that first class and lower class look roughly equal. The population, as we learn, is carefully controlled on this train. Poor and rich don’t matter in this contained environment, where currency is useless. Life—and the threat of ending it—is all these survivors can trade. This is the most terrifying aspect of this rigid society: everyone exists in his or her place, a have or have-not, without any hope of upward mobility. The most suspenseful movie I’ve seen in years, Snowpiercer will hopefully lead to more beautiful and twisted ideas from Joon-ho Bong.