By the time the hero sits down in a sushi bar to eat a live, wriggling squid, you'll have probably figured out whether ''Oldboy" is or isn't for you.
On the strength of this 2003 film and the previous year's ''Sympathy for Mr. Vengeance," fans of bleeding-edge genre mayhem have already proclaimed Korea's Park Chan-wook the next Quentin Tarantino/Robert Rodriguez/Takashi Miike/insert your favorite bad-boy director here. More than anything else, ''Oldboy" recalls Alfred Hitchcock with all restraint tossed to the wind, or Hitchcock's most obsessed devotee, Brian De Palma, at his most nastily inspired. (The split screens and Jo Yeong-wook's swooping orchestral score help.) Ingeniously structured, brilliantly shot, and very hard to take, this tale of revenge is without question the work of a master craftsman.
But it also requires that you check more than the usual amount of disbelief at the door and, in the final half-hour, moves from the spectacularly bent to a sadism that just seems pleased with itself. Park blows through taboos with such sinister brio that he seems to have forgotten they might be there for a reason.
For a while, though, this is as invigorating -- and as darkly funny -- as modern rogue moviemaking gets. ''Oldboy" introduces us to a businessman named Oh Dae-su (Choi Min-sik), feisty and drunk after a night out, and quickly throws him into a well-appointed prison cell. The location of the jail, the identity of his jailers, the length of his imprisonment, and the nature of his crime are all unknown. After 15 years of sanity lost and (somewhat) regained, Dae-su is released, seething with resentment, and his first stop is that sushi shop with the unfortunate squid. It's there, too, that he receives a mysterious phone message informing him he has five days to discover who took a decade and a half of his life and why.
In the ensuing quest for truth and dismemberment, Dae-su is accompanied by an old school buddy, Joo-hwan (Ji Dae-han), and by Mido (Gang Hye-jung), a lovely young sushi chef who is somehow drawn to this madman with the electric hairdo. Obviously, Mido either is or isn't to be trusted, but it's a measure of this director's skill with cinematic games that the answer to that riddle somehow manages to be both.
Any more and I'd give away the film's endless store of surprises, although it's worth mentioning that one of the villains has a dispassionate interest in human suffering that recalls the 1988 Dutch suspense classic ''The Vanishing." Anyway, individual scenes in ''Oldboy" carry more weight than the larger story line, and Park's imaginative control over his harsh, surreal dream world is often entertaining in and of itself.
For instance: The sequence in which an already exhausted Dae-su has to fend off dozens of attackers could have been filmed Hong Kong-style, with multiple angles and seizure-inducing editing. Park simply uses one very long tracking shot along a dimly lit hallway as the battle ebbs and flows, giving the scene a fresh realism and a fresher sense of humor.
In the end, though, the director's taste for surgical shock outstrips his interest in narrative logic. The film's final 20 minutes are a gross-out symphony of revelations, humiliations, and mutilations, and while geek connoisseurs will be slapping their thighs in rapturous disgust, the rest of us may be excused for feeling as though we've wandered into a party at an autopsy.
It may be that this filmmaker is better taken in small doses. In the pan-Asian horror trilogy ''Three Extremes," which played at the recent Sundance film festival and may get a theatrical release later this year, Park's entry, ''Cut," is a little jewel of malefic genius. ''Oldboy," by contrast, is the entire jewelry store, with each bauble bigger and colder than the one preceding it.
Ty Burr can be reached at tburr@globe.com.