As the American market for foreign-language films continues to shrink, at least one variety appears in little danger of extinction: those that combine arthouse respectability with grindhouse titillation, the more shocking the better. But by trying to appease audiences seeking staged sex as well as those looking for weightier matters, most such films end up satisfying neither. Catherine Breillat's Romance, for instance, mingled hardcore sex scenes with tedious musings on sexuality and identity, pleasuring only those with the highest possible tolerance for self-indulgence. (Hats off to anyone who can explain why the subtitles appear in the middle of the frame for the film's first 10 minutes.) It's nice, then, that director Sun-Woo Jang's Lies manages to have it both ways, offering eye-opening sex scenes as well as more than enough to contemplate on the way home. Adapting a novel banned in his native South Korea, Jang follows an affair between an 18-year-old college student identified only as "Y" (Tae Yeon Kim) and a sculptor more than twice her age identified as "J" (Sang Hyun Lee). After a phone conversation, they agree to meet for a sexual encounter, Kim's first, that develops into a full-blown affair. After a handful of liaisons, Lee reveals his love of sadistic foreplay, unveiling a shiny suitcase brimming with whips, rods, and other implements that Kim first accepts, then begins to employ herself. At first, Lies seems to exist to service its sex scenes rather than the other way around, and self-reflective moments such as Jang's interviews with the stars (both, remarkably, first-time actors) resemble mere artistic pretense, with handheld cameras used as a matter of budgetary expediency. But after a while, Jang's reasons for lingering on his lovers' increasingly involved encounters begin to reveal themselves. The film finds parallels between S&M sex and more traditional couplings, but also between S&M and other collaborative enterprises: In their sessions together, Kim and Lee establish boundaries, follow guidelines, and create a shared narrative, activities Jang quietly but insistently compares to all relationships, and to the filmmaking process itself. If the protagonist's relationship enacts a shared fantasy, it's only an exaggerated version of what virtually everyone does on a daily basis. Growing more playful and stylistically adventurous as it progresses, Lies also reveals a debt to the films of Wong Kar-Wai, particularly Happy Together, which similarly follows the ups and downs of an intense relationship. But Jang repays the debt by placing his own spin on the subject, and if the film occasionally suffers from its director's tendency to repeat himself, it remains provocative for reasons beyond its subject matter.