It's rare for contemporary movies to manage more than one tone at a time, like symphonies strung together from single notes. The South Korean director Bong Joon-ho, however, makes movies that resound with juicy, strikingly dissonant chords — one reason his deliriously entertaining monster movie The Host was an arthouse smash here a few years ago. A procedural mystery in which an aggrieved mother tries to clear her wrongly accused son sounds as routine as The Host did in outline: Eco-monster rises from toxic government spillage. But Bong's energizing snarl of moods and emotions results in the haunting Mother, an equally strange and startling mutation.
Mother keeps us off-guard from its very first shot, of an aging woman swaying sinuously in a field to music only she can hear. Identified only as Mother (Kim Hye-ja), she cares for a grown simpleton son (Won Bin) who's taken to heart all his mom's bad advice — especially about what to do whenever someone bandies the term "retard." When a girl is found murdered, with evidence nearby linking the son, Mother first plays supplicant to the careless, diffident police — then detective when the dead girl's missing cell phone offers a key to the mystery.
Bong specializes in scenes of comic volatility that sprawl in all directions. An encounter between Mother and the dead girl's grieving parent is a head-on collision of shame, fury, spleen and defiance, and the scene's tilt into near-slapstick only adds another layer of unsettlement. But there's never the sense that Bong is simply jerking us around by jamming gears, as in some of his countryman Park Chan-wook's baroque genre pieces. A jaw-unhinging mid-film twist violently wrenches the movie out of its familiar orbit, sure, but not for a cheap gotcha. Instead, Bong re-centers the mystery from a whodunit to something far more disturbing — a whydunit, with a gnarl of shared guilt at its core.
Culminating in a series of beautifully executed Hitchcockian setpieces, Bong's film never stops surprising us. The same is true of his astonishing lead actress Kim, who never seems to be channeling less than two conflicted emotions at once. She's too good for an Oscar. The last shot returns us to what may be Mother's most compelling riddle — the mystery of why she's dancing in that first shot