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.