There are dumb movies that think themselves smart, and there’s smartly conceived trash like Colony, which re-unites South Korean genre virtuoso Yeon Sang-ho with the undead. Following his loosely connected zombie trilogy of Train to Busan, Seoul Station, and Peninsula — the former of which set the world on fire, and is all set for a Hollywood remake — Yeon zigs in a brand-new direction, with a goofy action-thriller that zags at every turn, and makes its sprinting dead the central stars.

Granted, there’s a human cast to be found, all of them broad cutouts trapped in a combination mall/corporate office when all hell breaks loose. However, the plot depends heavily on their randomly-shifting morality, so they’re far more narrative instruments than living, breathing people. Much more central to the Z-lore this time is its definitive origin: a pathogen engineered by moustache-twirling bioterrorist Young-cheol (Koo Kyo-hwan), a scorned scientist hell-bent on proving a point when he injects his former boss with a viral agent during a company convention.

The standalone saga accelerates with aplomb, as the usual conventions of biting, writing and puking give way to rage zombies that scamper on all fours and seem attracted to light, and anything vaguely human-shaped. They’re extremely primitive, and each time they flop around on the building’s marble flooring, the camera follows suit, weaving and bobbing alongside them.

Trapped in the quarantined building, as the virus spreads, are conscientious former bioengineer Se-jeong (Gianna Jun, in her first film appearance in a decade), her caring ex-husband Gyu-seong (Go Soo), kindly building security guard Hyun-seok (Ji Chang-wook), his tech-savvy, paraplegic sister Hyun-hee (Kim Shin-rok), and an assortment of other stock types who alternatingly kick off action, exposition, or both. However, it isn’t long before Colony reveals its novel conceit. Just when it seems like our human heroes might outsmart the breakneck beasts, they suddenly stand at attention, in an agonizing trance, from which they emerge having collectively learned the ways in which the humans have been trying to escape or evade them. Soon, they even stand on two feet, as though evolving in real time… while also spreading a strange, white mucus across the building’s interior, until it resembles an Alien sequel.

The monologuing Young-cheol is all about collective consciousness, a cloud-themed impetus that draws on modern anxieties of a technological surveillance state, which ends up embodied by his rage zombies. They share information through a combination of psychic and fungal means, so they’re constantly learning and seeing things through each other’s eyes. It’s perhaps the most fascinating biotechnological development in recent fiction, rivaling Apple TV’s Pluribus for the way it makes even the total loss of individuality seem kind of alluring. You know, except for the part about being turned into an icky, hungry cannibal. That part still sucks on paper. But if any living director can make zombies seem cool, it’s Yeon, who captures his creatures’ springy momentum like he’s filming Cirque du Soleil.

Everyone in the movie’s fiction is totally dialed in, but their po-faced approach to the material doesn’t stop Yeon from having fun. The humans launch themselves at their attackers. The zombies learn to throw each other great distances, and eventually pick up guns. There’s even a subplot involving feral, frozen zombie Macaques, and a very fun dilemma that positions Young-cheol as both the ostensible zombie king as well as the only means to engineering a cure, granting him a hilariously convenient plot armor as his undead underlings do his bidding.

All the while, every single actor and extra who plays a zombie comes off as an absolute star. These aren’t your standard shuffle-and-sprint biters; their roles require both athleticism and shedding any and all self-consciousness in order to perform the creatures’ practically dance-like motions, especially as they grow in sync. The world outside the locked down office building certainly exists — there’s a perimeter, cops, scientists, and all the staples of disaster cinema — but it all serves the function of further contextualizing all the gonzo goings-on inside, as the stakes constantly evolve, and the zombie threat continues to morph.

Yeon’s use of physicality, of gooey textures, of alternating noise and silence, and of the sudden rush of eruptive action, all ensure that Colony is a complete blast. It’s buoyed by the notion that the zombie genre has long run its course, and the only way to resurrect it is by turning its established “rules” completely inside out. And while there are several conveniences to wade through across its 123 minutes — which feel more like shortcuts than cunning swerves — every decision ends up in service of a rollicking good time.

Siddhant Adlakha (@SiddhantAdlakha) is a New York-based film critic and video essay writer originally from Mumbai. He is a member of the New York Film Critics Circle, and his work has appeared in the New York Times, Variety. the Guardian, and New York Magazine.