Mother (Korean)

Is there a sweeter word than “mother”? It (or a simplified version of it) is usually one of the first words a baby learns to say. In every language it suggests love and nurturing, as well as fierce protection. You do not get between a mother and her young. You do not threaten a mother’s children, nor do you threaten a child’s mother. You have no problem identifying your dad as something of a bastard if that’s the case, but your mom — she is revered and honored, no matter what faults she may have.

This natural respect for motherhood is at the root of “Mother” (“Madeo”), a fantastically unsettling mystery-thriller by Korean filmmaker Bong Joon-ho (whose “The Host,” from 2006, was one of the more entertaining monster movies of the decade). Bong starts with the basic premise that a mother will do anything to protect her child, then takes that premise to its logical — yet somehow also completely insane — conclusion.

The mother in question is Yoon Hye-ja (Kim Hye-ja), an herbalist and unlicensed acupuncturist who lives in a small South Korean town with her son, Do-joon (Won Bin), as her only companion. Do-joon, in his mid 20s, is somewhat developmentally disabled, probably about 7 years old in terms of emotional maturity. He’s able to get along OK, though, requiring just a little extra attention from his vigilant mother.

Mrs. Yoon is only too happy to provide it, too. Protective by nature, she has a worried, Meryl Streep-y face, and expresses concern about Do-joon’s friend, Jin-tae (Jin Goo), whom she considers a bad influence. Do-joon and Jin-tae get into a bit of trouble with some local rich dudes at the town’s country club after a minor hit-and-run accident … and then the movie kicks in to high gear.

A teenage girl is found murdered. The evidence points to Do-joon, who we know saw the girl before her death. A police detective, Je-moon (Yoon Je-moon), already acquainted with the Yoon family — it’s a small town — knows Do-joon is harmless. But facts are facts, and these facts are incriminating. Has Do-joon been framed? The cops can’t do much about that, not when whoever did the framing has done such a thoroughly convincing job of it. It’s up to Mom to find the real killer.

Yes, it’s Middle-Aged Korean Mother: Amateur Detective! What a kitschy premise, and what a bang-up job Bong does with it. (He wrote the screenplay with Park Eun-kyo.) The whodunit elements are superb, with just the right mixture of red herrings, twists, and unforeseen resolutions. As more facts about the murder victim come to light — think Laura Palmer in “Twin Peaks” — Mrs. Yoon is taken down a thorny path of clues and misdirections, searching for a missing cell phone, dealing with the girl’s lunatic grandmother. Through it all, her only goal is to clear her son’s name. She is single-minded about it. I recommend you do not get in her way.

I don’t know much about Kim Hye-ja, the actress who plays Mrs. Yoon. Asian Media Wiki reports that she was born in 1941, earned an award for her 1982 feature-film debut, and has a “warm and kind image” that has been represented in a long career in Korean TV. What I know is that if “Mother” were an American film, Kim Hye-ja would be nominated for an Oscar. Her performance is almost perfect: controlled, subtle, emotionally powerful, completely convincing. No matter what odd things the film requires her to do — and Bong starts the movie with her in a field, dancing sadly to a gentle strain of elevator music — Kim is up for it.

Bong’s direction is equally impressive. He surprises us without resorting to cheap tricks, reveals shocking information without cheating. As with most great mysteries, the outcome, when it is discovered, turns out to have been inevitable: Now that we know the facts, OF COURSE this is how it had to end. That un-gimmicky structure is what makes the delightfully dark and twisted journey so enjoyably satisfying.

A- (2 hrs., 8 min.; Korean with subtitles; R, a lot of harsh profanity, some strong sexuality, some fairly strong violence.)