Lee Seung-won’s _Three Sisters _is a quietly triumphant masterwork that reminds us that even the most banal-seeming of storylines can become mesmerizing in the hands of a gifted artist. Deftly interweaving stark drama, gentle comedy, and pointed social themes, the film also features tour-de-force performances from its three leads. As with many adult siblings, these are so different from one another that it’s hard to imagine their shared upbringing (black-and-white flashbacks eventually help). The eldest sister is a florist who’s always apologizing, and has no one to share her frightening secret with. The middle sister is a devout Catholic with defiant children and a philandering husband. The youngest (played by Moon So-ri, who also produced the film) is an alcoholic facing writer’s block, whose stepson is less than enchanted with her. The sisters are brought together by their father’s birthday party, where childhood traumas, old wounds, and an errant family member all contribute to an explosive emotional climax.