Monica Bellucci’s sneer is a thing of wonder, so why have so few directors used it properly? When allowed full rein to her sense of irony, as given her by Giovanni Tortorici in “Ketticè,” Bellucci has few equals in her ability to project self-aware drama queen with just the right dose of camp icon. Hers is a supporting role, as the quasi-caricatured bourgeois mother of a far more authentically drawn teenager, but the young writer-director deliberately sets genuine adolescent nihilism off against the stereotyped adult world, rejuvenating a time-tested formula with the story of an aimless rich kid that feels anything but aimless.

As proven with his terrific debut “Diciannove,” Tortorici masters the directionless depths of the under-20 set, and while some may protest the shallow depiction of working-class kids as opposed to their better-off peers, few will gainsay his thoroughgoing feel for character and mood as conveyed via camera angles and space.

The evocative voice of Lebanese singer Oumeima El Khalil accompanies a panoramic view of Palermo, her song’s dissociation from the locale and its simultaneous, unexpected suitability working in ways akin to the soundtracks of Luca Guadagnino, Tortorici’s mentor and producer. It’s 2012, Facebook is as indispensable as an iPhone 5, and Giulio (Salvatore Gallina) is on the verge of failing most of his subjects. In the first of several amusing slow-mo pans, the camera moves from fed-up teacher (Davide Cirri) across to bored witless students, continuing its sluggish progress outside the building and into the carpark, resisting normal speed until Giulio starts the ignition and “You Spin Me Right Round” pours forth from the radio.

This kind of playful yet expressive use of visual language is what makes “Ketticè” such a fun watch: When Giulio gets in his car right after kissing his girlfriend Elena (Ida Poerio), the camera sits on the floor to make the 16-year-old look like a big man, but after receiving a break-up text, the viewpoint switches to eye-level and returns him to normal teen-size. Not that he’s heartbroken, though the new angle makes it easier to see how he forces out a tear, takes a selfie, and posts it on Facebook.
 
The only real hardship Giulio faces is figuring out what he wants to do when he grows up. He lives with his parents, Vittoria (Bellucci) and Antonio (Tommaso Cristiano Wirz), in the family’s historic palazzo, and attends a private school where small classes make for tight-knit camaraderie but don’t guarantee that any learning sinks in. Neither do his grandmother’s attempts to impart culture, observed in a hilarious dinner table scene during which Vittoria launches acidic barbs at her impervious mother-in-law (Stefania Raffadali) while passive Antonio lets it all wash over him.
 
As bored at home as he is in school, Giulio becomes fascinated by Ketty, aka Ketticè (Rachele Testagrossa), a girl from the wrong side of the tracks with a reputation for provoking catfights. Confident, street-smart and far removed from his world of privilege, Ketty knows where to score the best weed in town, and thanks to Giulio’s generous allowance, the two head to Palermo’s Bonagia district where he drops €20 a day buying smokes from a guy dealing in a square presided over by a statue of Padre Pio. It’s hard to say whether Giulio becomes more dependent on the pot or the feeling of very mild danger he gets from hanging out with a girl whose hard-edged reputation is an attention magnet, but either way, everyone’s beginning to notice.

There’s an obvious contrast between Giulio’s world and Ketty’s. In his circle, where it’s not unusual for a 14-year-old to have their own car, the antics of the lower classes are a spectator sport, shared across Facebook posts and then forgotten. They’re protected by their parents’ money, whereas Ketty has no prospects apart from more bitch-slap fights with girls whose cheap makeup and nail extensions are their most distinguishing features. Whether deliberate or not, scenes with Ketty’s regular crowd have a built-in sniggering element not felt with the private school kids who don’t need to posture or defend themselves. We certainly laugh with Vittoria’s exasperated outbursts, but Bellucci’s deliciously ironic flamboyance means we don’t laugh at her in the way we do when Ketty’s hard-ass rivals seek revenge.

All too often when directors seek to get inside an adolescent’s world, the results unintentionally highlight the psychological distance between filmmaker and subject, but both here and in “Diciannove,” Tortorici understands that endless ennui isn’t the same thing as permanent emptiness, and angst isn’t the most interesting thing about a teen. Clearly he listens: to his actors (many of whom are first-timers), to younger generations around him, to the honest memories of his own youth. “Ketticè” shows how he’s also confidently playing more with the grammar of cinema, putting it to use according to character and mood, and in so doing solidifying the promise of his debut.