Part murder mystery, part domestic melodrama, part dark comedy, Mother is also a wholly original treat that confirms writer-director Bong Joon-ho’s touch with multiple tonalities, as well as his status as South Korea’s preeminent modern auteur.

Simple peasant Hye-ja (Kim Hye-ja, above) is the profoundly devoted single mother of 27-year-old Do-joon (Won Bin), a naïve, memory-impaired man-child whose affability helps mask the fact that something isn’t quite right with him. Walking home drunk and alone one evening, Do-joon encounters a schoolgirl who he follows for a bit before she disappears into a dark alley. The next morning, she’s found dead in an abandoned building. Do-joon is eventually arrested for her murder, and an apathetic police force doesn’t seem much interested in investigating Hye-ja’s insistent refusals that her beloved son could ever possibly be guilty. Embarking on an obsessive quest to prove her son’s innocence, Hye-ja at first focuses her efforts on his scummy friend Jin-tae (Jin Goo), but slowly learns more and more about the victim, which expands her suspect pool.

Like the works of David Lynch or Alexander Payne, Bong’s films unfold in mannered worlds where comedy and drama are hopelessly commingled. Owing to the combination of both this and its innate foreignness, Mother is unnerving — you don’t really know what it wants or expects from you as an audience member. Despite the general dramatic success of its homicidal mystery story strand, Kim’s bravura performance is the glue that holds everything together; with her plaintive eyes, she makes you deeply feel both her character’s mania and sadness, which is crucial to Mother‘s artful navigation of those treacherous pivots in tone. The film’s hold slackens a bit, understandably and almost necessarily, after a great third act shock, but one doesn’t greatly begrudge Bong the privilege of closing things out with an eerie, melancholic denouement. (Magnolia, R, 129 minutes)