“Train to Busan” is a zombie film that yet again explores our collective anxiety that, just maybe, the person sitting next to you who looks, smells and sounds nothing out of the ordinary may succumb to the universal violent impulse to bite your face off. And like many of its more socially conscious kin, it additionally wonders whether tearing off someone’s face is the preeminent moral standard to which we want to hold our species accountable. It’s a film that understands its rails have been skidded to the point of erosion, and that only a vigilant, momentum-savvy scene-to-scene vigor can safeguard it from the pangs of forgettable mediocrity that have already gutted three-fourths of its genre. Thankfully, director Yeon Sang-ho proves to be an able conductor, resulting in a cinematic journey that, despite tremendous luggage, grips and entertains at many turns and stations.

Our hero, Seok-woo, is a negligent father who divorced the mother to wed his work. He is primly clothed in an Arendtian disregard for those suffering from his company’s ruthless policy. But like in most corporate sociopaths living on the brink of Armageddon, a faint ember flickers in Seok-woo’s stony bony heart, whose warmth and light he tirelessly directs toward his daughter, for whom he is even willing to purchase the same video game console twice, intention notwithstanding. In an effort to make up for his negligence, Seok-woo decides to accede to his daughter’s one genuine request: to catch a train to Busan and visit her mother there. Seok-woo, anxious about his daughter’s safety, decides to accompany his daughter. The two board the train along with several genre stereotypes: the Jock armed with the ever useful bat, the Homeless Man, the Cool Man and his Pregnant Wife, the decidedly less pregnant Girl and the Authority Figure whose sense of human decency falls first victim to the apocalypse. Unfortunately, there too boards an infected stowaway, who tries with tears and torn cloth to suppress the disease in the train’s bathroom stall. One of the attendants pays her a concerned visit, and all predictable popcorn hell breaks loose.

There really is no reason to list the names of most of the cast; the characterization in the film leaves only Seok-woo to speak of. Only he possesses a tangible arc, which taken alone isn’t too terribly impressive. The plot unfolds the changes and continuities of his character at a digestible pace, but the issue is that Seok-woo substantially interacts with only one object in the narrative, that being his disembodied conscience masquerading as his daughter. In addition to providing the audience with a beacon of paternalistic empathy, she is the vulnerable but compassionate child in a world filled with adults weak and vile at heart, whose pleas and counsel trigger the imminent demarcated step of Seok-woo’s eventual redemption. The rest of the cast is furniture, whose lives and deaths enforce the thickest bullet points of the daughter’s admonitions, nudging and tugging our protagonist toward heroism.

This problem with the protagonist’s arc hemorrhages into a more disturbing kind that would prick a longtime fan of Sang-ho when the zombie fiasco begins in earnest. Director Sang-ho first made his name as an animation director, who, equipped with meager resources, produced two obscure but impressive works of commentary on contemporary Korean society: “King of Pigs” and “The Fake.” What impressed about these movies were the interlocking inner worlds of their psychically ruined casts culminating in spectacularly violent twists that provide cathartic structural closure to the tragedies boiling beneath the surface texts. Here, in his first live action feature, Sang-ho has everything he did not — time, money, actors, recognition –— but the movie rings that much hollower. The awkward quarter-smiles of his complicated characters are replaced with Korea’s coolest man Ma Dong-Seok’s winning grin. Sang-ho’s once frenetic and at times frankly comical (in no small part due to his pittance of a budget) exertions of violence have become polished and accessible, at the loss of his poor man’s aesthetic that afforded the sense of psychological instability and unease that would have much more touchingly portrayed the occasional outpouring of shame and guilt on the part of the train’s survivors. And as if to officially declare the old Sang-ho dead, the conclusion of Seok-woo’s arc at the climax of the film is presented with every sin in mainstream Korean cinema’s maleficarum, from slow motion to sad music to saccharine monologue. Without a doubt, the film despite its fun, represents a regrettable deviance from the exciting trajectory suggested by his previous work.

But at least it’s fun. In the stead of Sang-ho’s old artistic vision, his general ability as a filmmaker and the personalities of its actors sufficiently animate this feature to leap several miles beyond most of its flick competitors. The aforementioned Ma Dong-Seok is a national treasure, an actor who oscillates between a runaway hare’s affability and the pursuant tiger’s ferocity without a moment’s reluctance. Special props must additionally be given to the extras. At a distance, the red and gray functionally resemble the ashen mutilated flesh of the living dead, and the camera is wise to not linger too long among the zombie hordes. What’s more, the zombies cry, twitch and sprint in a way that defies second-to-second expectation; at every beat, the zombie moves in a way just slightly foreign to human behavior. This subtle, unjustly unappreciated physical acting found at every scene and in every underpaid extra, is the most accomplished aspect of the film. Together with Dong-Seok, the zombies expertly stage the flights and fights that constitute the central appeal of the movie. Each of these sequences makes full use of the setting’s unique, compartmentalized geography. The zombies are rushing from one end of the cart, and the heroes need to get to the other end, while warding off the nearest pursuers. It’s a set piece that clearly communicates its simple objectives (literally point A to point B) and mechanisms of tension (“there’s one coming from left under!”), corresponding neatly with the general accessibility that characterizes this movie.

The film was a colossal hit in Korea, and in overview and hindsight, it’s not difficult to see why. Like most mainstream successes, “Train to Busan” employs both spectacle and emotion with a child’s candor, and combined with the sheer novelty of a zombie apocalypse occurring in such familiar ecosystems, it was nigh impossible that the movie fail in its native market. Aside from the physical violence, it really is a family feature. While it’s regrettable that Sang-ho’s traded in his signature sensibility for a fun flick that will probably be forgotten in time as one of the myriad influences that shaped Korean mainstream cinema of the 2050s, one hopes that the film at least sheds light on the rest of his more interesting filmography and gives commercial platform for his vision to return in force.