Fernando Guzzoni’s Jesus, the latest cautionary you-are-there-as-the-kids-go-wild drama, shares many hallmarks of its genre: loose, improvisatory scenes of drug use and bullying cruelty; frank sex and violence that, while simulated, certainly seem to have hurt and aroused the actors; a cast you might fear is too young to be exposing themselves onscreen this much; a sense that we're being warned about the promiscuous abuse of young flesh even as that’s also the lure to get audiences into the theater.

Though it’s based on a true story, the action, centered on an 18-year-old Chilean named Jesus (Nicolas Duran), builds toward tragedy without any sense of inevitability — one night, things simply get out of hand. Still, Jesus boasts a charged verisimilitude. The opening scenes capture the peculiarly intense aimlessness of a bad kid’s day. We witness lightly sensitive Jesus — distinguished as an artsy dreamer via the bass clef tattooed on his neck and his gauged ears — participate in the kind of pop-squad dance competition that suggests a family film, get chewed out by his dad (Alejandro Goic), buy a cellphone, get sucked off by a young woman in a park. Then — in a lengthy, convincing sequence that may trigger fight-or-flight in anyone who has ever been trapped for a night with teen louts — he tries to fit in with drunk toughs as they haze, whale on and rob a young man reputed to be gay.

Offhand and so naturalistic that they seem observed rather than staged, these scenes, set in the wee hours, achieve a sickening power, stirring that sense of a night lurching out of control. (Guzzoni’s camera often seems to follow the action rather than anticipate it.) The victim winds up comatose, and our aimless Jesus faces grief, guilt and a terror of getting implicated in the crime. Meanwhile, he surprises us with his second sex scene, so much more passionate than the first: a ferocious stroke section with another young man, their connection all the more tender for the moment's urgent roughness.

Does Jesus' fear of the exposure of his own sexuality mitigate at all his uneasy participation in the earlier beatdown? Of course not. The film runs just 82 minutes, but the tense final act, which finds Jesus confessing to his father and then trying to work out what to do, investigates its moral quandaries with a rigor this kind of bad-seed street-teen movie usually can't manage.