Kim Jee-woon’s “I Saw the Devil” is a thriller that makes you wish you knew how to scream “O.M.G.” in Korean.

It is a jaw-droppingly-violent tale of a government agent who sets out to avenge himself on the serial killer who kidnapped and murdered his wife.  Your jaw will drop at the level of gore and violence long before that agent (Lee Byung-hun) grabs a murderer by the jaw and tries to “make that smile permanent” in one of the film’s more grisly moments.

It’s a cruel movie that, had it been filmed in English (It’s in Korean) might be dismissed as “torture porn,” which is pretty much what it is. Characters are brutalized, beaten, sliced and diced and even eaten. But since it’s from a leading Korean practitioner of screen ultraviolence, it fits into the hipper “K-horror” genre, not to be confused with “J-horror” (Japanese horror), as if that makes it somehow more palatable.

“I Saw the Devil” opens Friday at the Enzian, evening shows only.

On a snowy night, a gorgeous young motorist (Oh San-ha) is stranded. A small bus pulls up nearby and a hooded figure walks over to offer help. No, she says. She’s just been on her cell calling a tow truck. He insists, she resists. And then he shatters her windshield and delivers one of the most savage, heart-rending beatings I’ve ever seen on film. A hammer to the head is going to make a mess, even if the victim lives.

Then this monster ties her up, comments on how easy she will be to butcher, and ignores her pleas — “I’m pregnant.”

But her grief stricken husband (Lee) resolves, over the parts of her corpse that are recovered, to avenge her. “I’ll make him pay for your pain,” he hisses. She was alone because he works too much, providing security for diplomats and the like. He is wracked by guilt. And  like the Liam Neeson character in “Taken,” he has “particular skills,” the ways and means to make that revenge happen.

Using info provided by his wife’s retired cop dad (Jeon Gook-hwan), Agent Soo-hyeon hunts down suspects,  torturing each in turn as he tracks the real killer. But this isn’t a whodunnit. We and he figure out that it’s the brute Kyung-Chul (Choi Min-sik) early on. That’s when the real cat-and-tortured-mouse games begin. Remember, Soo-hyeon doesn’t want to just catch the guy. He wants him to pay for his wife’s pain. The ways he sets out to do this will make your skin crawl.

Kim Jee-woon is established enough to be included among the three directors telling three horror stories sequel to the Asian horror sampler “Three Extremes.” He isn’t known for subtlety. His trademark is not flinching, never shying from bludgeoning characters well past the point that most directors would yell “Cut,” not hesitating to show what serial killers might want to do with that flesh they’ve procured. That makes for an overly graphic movie and an overlong one.

With “I Saw the Devil” Kim tries to be both voyeuristic and moralistic, putting us in the murderer’s shoes, making Soo-hyeon weigh the possibility that his actions are turning him into the same monster he is hunting.  Avert your eyes at the blood spatters. Wince at the director’s efforts to make light of the crimes — comically inept cops, wise-cracks from the killer even as he suffers captures and re-captures, complete with fresh, gruesome injuries, at the hands of Soo-hyeon.

But this wallow in viscera is a genuinely visceral experience. We dragged along as murderous hero and mass-murderous anti-hero pursue each other across a Korea littered with potential victims and killers.  It’s only when the shock of the gore wears off that we consider how little “moral” there is to this morality tale, how horrifically it treats women, how much it depends on super secret agent gadgets and how long it will be before you ever ask for a steak “rare” again.

 Cast:  Lee Byung-hun, Choi Min-sik,  Oh San-Ha,

Director: Kim Jee-woon

Running time: 2: 21

Rating: unrated, with gruesome, graphic violence, nudity, abusive sexual situations