Of the automated modes of transportation mankind has developed, trains have always been the most surprisingly cinematic. You would think that such a setting, comprised of cramped spaces and narrow passageways, would ultimately be more suitable for a more intimate art form like the theater, yet some of the most memorable moments in film history have incorporated trains. While there’s always a rotten example like the Atlas Shrugged films, there will always be Rick Blaine having his heart broken on the last train out of Paris, or Bruno and Guy discussing how to pull off the perfect murders in a shared compartment, or even the Whitman brothers riding through India on the Darjeeling Limited. What is it that makes locomotives an indelible, and irresistible, hallmark of cinema? I think there’s a claustrophobia inherent in a train that forces a group of characters to confront each other, as well as the notion that each boxcar, let alone the entire vehicle, represent a more contained and controlled environment meant to counter the chaos and unpredictability of the outside world. All of these core traits and tropes fuel Bong Joon-ho’s Snowpiercer, a dazzlingly thrilling blockbuster that provides a much needed alternative to the soulless and personality-deprived Hollywood dreck currently in multiplexes.

The premise is an intriguing one, albeit one that requires you to suspend your disbelief. Global Warming prompts our scientists to develop a solution that inadvertently sends the Earth into a second Ice Age. The human survivors, what few that remain, have taken refuge on the titular train which has been in perpetual motion for seventeen years. The privileged few live in relative comfort in the front cars whereas the unlucky majority dwell in the tail section, forced to live in their own filth and have “protein bars” as their only dietary option (though the actual source of that protein is far from savory). These unfortunate souls find leadership in Curtis (Chris Evans) and the wizened Gilliam (John Hurt), both of whom are planning a revolt that will result in them gaining control of the engine. Several others have tried, and failed, in the past to gain control of the train from Wilford, the creator of the train. The only thing these rebels have on their side is desperation, but that might be just enough to finally succeed.

The array of characters encountered on the train are garish, horrifying, or comical, often all at once. Curtis and his companions earn an uneasy ally in Namgoong Misu and his daughter Yona (Song Kang-ho and Go Ah-sung, respectively, playing an extension of their roles in Bong’s classic monster film The Host). Misu knows how to unlock each door on the train, but he and his daughter demand Kronol, a rock-like hallucinogen, as payment. Our heroes must also contend with the villainous Minister Mason (a delightfully dastardly Tilda Swinton) and her legion of lackeys who, with their vibrantly colored and festive outfits, look like they’ve stepped out of a lost Terry Gilliam film. Indeed, Bong takes a few pages from Gilliam’s best work by fluctuating between the goofy and the grotesque without giving his audience emotional whiplash. Like the antagonists in Brazil, Mason and her associates are both sources of ridicule and intense menace due to their emotional isolation. One brilliant sequence takes place in a train car that is meant to be a kindergarten of sorts that has a twisted sense of humor and, ultimately, a pervasive sense of horror. What makes Snowpiercer truly remarkable is Bong’s ability to navigate tonal shifts without ever coming across as insincere or cheap.

There are many other memorable set-pieces scattered throughout the film, often both thrilling and visually arresting, including fight sequences in a dark boxcar and a hazy spa. I could list more of the strange sights and sounds Curtis and our heroes encounter, but that would spoil some of the surprises the film has in store. I’m not giving anything away by saying that there are a few revelations waiting for Curtis when he finally makes it to the front of the train, but they don’t feel like cheap gimmickry but rather earned twists that don’t betray the film’s thematic concerns regarding social order and its necessity (or lack, thereof) in the face of complete oblivion. The climax of the film becomes a little verbose in spots with its bevy of monologues, but it works because the audience has an emotional stake in the hero’s journey. When Curtis explains his motivation for reaching Wilford (who may not even exist) and the engine, his earlier reluctance at being seen as a leader seems more like the natural reaction of a man haunted by severe demons and less like the pat prerequisite for an action movie character, and it’s Evans’ surprisingly affecting performance that gives Curtis conviction.

There are moments that beggar belief, from small logistical quibbles (who is, if anybody, maintaining the tracks that have ensured the train’s been running for seventeen years?) to larger flaws that border on the ridiculous (one thug becomes incredibly persistent to kill to the point that it becomes absurd without necessarily being amusing). Nevertheless, Snowpiercer excels as an action film that, while not the most intellectually stimulating of recent science-fiction films, still has a beating heart and a clear-eyed conscience on what goes into maintaining societal hierarchies when the alternative is sheer chaos. Finally, consider the boldly ambiguous ending Bong chooses. The Weinstein Company, which distributed the film, wanted to insert a voiceover that would offer unneeded clarity for the audience, but Snowpiercer isn’t meant to comfort moviegoers into a lull. Not when it’s so uncertain about our future as a society and as a species.