In a number of not insignificant respects, the experience a South Korean will have viewing the new whodunit  from writer-director Bong (The Host) Joon-ho  will differ from that of an American watching the same movie. The story concerns a mentally disabled young man accused of murder and the widowed mother who pursues the real killer when police lock up her son and close the case.
Few American moviegoers will appreciate, for example, the extreme makeover undergone by former teen idol Won Bin  in his preparation for the role of twentysomething local joke Do-joon. The character’s a marvelously intricate creation carried off brilliantly. Just as few — and this is truly a shame — are likely to find themselves in on the filmmaker’s little joke in casting 68-year-old Korean television legend Kim Hye-ja as the title character. The actress has spent much of the past 30 years playing traditional maternal parts. Her role here carries shock value audiences in the West can’t begin to imagine. Conversely, how many South Korean viewers will describe the picture as Hitchcockian?
More important, of course, is what viewers everywhere will share: a cinematic experience that takes us into rarely explored psychological terrain, almost never proceeds as we predict and craftily subverts the genre.
Hye-ja’s unnamed character is an herbalist and acupuncturist with a tiny shop in a nondescript village. Her real job, though, is keeping her son out of trouble. Do-joon would be at the mercy of a thousand forces even if his best friend, Jin-tae (Jin Ku ), weren’t a local hustler and thug.
When Jin-tae asks Do-joon whether he’s ever slept with a woman, the young man answers, “My mother.” We realize this isn’t the simple bit of comic dialogue it seems at first when Do-joon crawls into bed with his mother later that very night and rests a hand on one of her breasts, and she responds only, “It’s so late.”
The plot hinges on what happened only moments before. Earlier that evening, Do-joon drank too much while waiting for Jin-tae at a bar; the owner asked him to leave after he tried to pick up her daughter. On the way home, he crossed the path of a fetching schoolgirl named Ah-jung, whom he followed until she disappeared down a dark alley. In the morning, her body is found neatly folded on a hilltop balcony overlooking the town.
What initially appears a twisty riff on uncritical devotion slowly but surely reveals itself as something infinitely more twisted. Joon-ho is a master at lacing pulse-pounding suspense with offbeat humor, but here he adds a new darkness to the mix. It’s easy to understand, for example, why a parent would try to protect her cognitively challenged child. But what are we to make of the fact that, when he was 5, she tried to end his life?
This is a constantly surprising, subtly acted and masterfully directed mystery propelled by Lee Byeong-woo’s score, which echoes Bernard Herrmann’s soundtrack for The Wrong Man one minute and Stanley Myers’ tender guitar theme from The Deer Hunter the next. The movie opens, in fact, with a sequence in which we watch Hye-ja alone in a swaying field dancing gently to this music.
The instinct of the viewer, I think — whether Korean or American — is to interpret this as a gesture of victory and contentment. The next two hours flash back through the days leading up to that dance in the field and astound us with the measure of our miscalculation. With a final act likely to leave M. Night Shyamalan’s jaw on the theater floor, Joon-ho’s latest features the mother of all surprise twists.