The next time you find yourself grumbling through another Hollywood pageant of high school social strata, consider the dubious French alternative. When not sunbathing nude, the rangy adolescents of “One to Another” sulk, bicker, philosophize about sex, and strike poses in the luminous southern France countryside. These rural youths, toned specimens of Gallic beauty, are trying to cope after a friend’s brutal murder, which means they exist mainly as attractive conduits for pontifications on mortality and bodily desires.

Filmmakers Pascal Arnold and Jean-Marc Barr based their mannered, artificially intelligent film on an actual homicide in a small town. The real-life murderers never fully explained their actions, and with an existential whoosh, “One to Another” rushes to fill that void with pretentious recriminations among the victim’s shocked friends and a pervasive, enervated sensuality.

Lucie (Lizzie Brocheré) is the moppet-eyed sister and possible incestuous partner of the severely sexy deceased, Pierre (Arthur Dupont). She undertakes a roundabout investigation of his murder, mostly by sleeping with the cop on the case and with a guy who might have been an enemy. “One to Another,” which opens today at Quad Cinemas, also freely shuffles in scenes from the past, so that Pierre is still a powerful presence, the idolized sexgod at the center of this shattered circle. “Only a body can know another body,” he proclaims to Lucie with academic certainty.

In the seamlessly intermingled flashbacks, Pierre rocks out with his band for the locals and wrestles suggestively with his sister (who has a similar strawberry birthmark). He’s also a prolific independent contractor in the sex trade, and after turning tricks for a middle-age john, he lands a new gig propelling orgies to new heights. Pierre’s technique is so inspiring that his pal Baptiste (Nicolas Nollet), clinging to him on a motorcycle, asks to watch him in action some time.

But Baptiste and the others are so interchangeably morose that even Lucie’s screechy machinations are a welcome relief. She tries to seduce a local man-child whom she thinks has a sixth sense about her brother, but the lug in overalls is preoccupied (“My sadness prevents me from seeing”). The cop turns out to be both bad in the sack and lazy at his job, willing to let the department dismiss Pierre’s case as the handiwork of an outsider to the town.

Messrs. Arnold and Barr are content to let their angsty teenagers drift along without much of a narrative push. Their young cast is beguiling while lounging about, but they’re dropouts when it comes to the sustained demands of more involved emotions such as grief (especially Ms. Brocheré). You could attribute that to age-appropriate indifference or lingering shock over the murder, but more likely it’s because “One to Another” just isn’t so invested in exploring their feelings.

In fact, for a movie so focused on sexuality and mortality, “One to Another” can feel disconcertingly removed. The directors avoid the sometimes sleazy voyeurism of a Larry Clark film, but they haven’t found a way to bring out their characters. Even a fraught visit to Pierre’s cremation ceremony fails to make a dent. The film perks up noticeably whenever Pierre appears, but it is otherwise shapeless, like the hazy memory of a dull summer vacation.

In retrospect, the movie’s opening shot seems pregnant with the filmmakers’ ambivalence about how to bring their material to fruition. The band of friends is visible as only head-to-toe shadows on dirt, dancing, posing, and beat-boxing. As the nifty image is held on for several beats more, you begin to realize that the vocal stylings are probably incidental to the foreboding reference to Plato’s cave. School’s out: Let the sensual ennui begin.