In Theaters: Jennifer's Body

"Hell is a teenage girl," viewers are warned in their introduction to Jennifer's Body, a funny, brainy, mildly flawed effort that should at least temporarily put to rest the debate over whether Megan Fox is more than just a pretty face. Her performance is indeed high among the reasons to see the film, as are those of Amanda Seyfried and Johnny Simmons and the bleaker-than-ever genre conflations of sex, youth and death. To wit: If hell is in fact a teenage girl -- a notion both screenwriter Diablo Cody and director Karyn Kusama purvey with a bracing lack of irony -- then where does that situate the men who chase her? And are all hells alike?

As it should, Jennifer's Body stops short of answering that question, instead choosing horror as the prism through which to bend the hot light of boy-craziness and sensationalism. As it shouldn't, it stops short of a lot else as well: An avowed fan of Italian gore and other exploitation derivatives, Cody either lost her nerve or an argument that would have given Body the truly vicious, knockout horror punch it needs. The gutted corpses of Jennifer Check's victims defy clique and other social categorization; they are unanimously intended for consumption only, much the way the small town of Devil's Kettle is devoured by the media after a bar fire -- and later Jennifer -- claims local residents' lives and the community's innocence alike.

High-school bombshell Jennifer (Fox) and her geeky, earnest best friend Needy Lesnicky (Seyfried) were there. Alas, Jennifer herself may have helped trigger it with her plan to seduce the lead singer (Adam Brody) of the emo-confection rock band visiting on a regional tour. That mysterious, exquisitely staged blaze ensues; Jennifer and Needy escape with their lives, but only Needy makes it out with her senses. Her friend rolls off with the rockers, who it turns out, are just in town scouting for a virgin they can sacrifice in exchange for devil-aided stardom. The next time Needy sees Jennifer, she's a sliced, diced, grinning, demon-possessed mess, bleeding from apparently everywhere and vomiting her thick, black guts on to Needy's kitchen floor.

Jennifer's fine the next day, driving her pal to distraction and Needy's boyfriend Chip (Simmons) to wonder if his girlfriend might need counseling. It is the morning after the biggest tragedy their town has ever seen, after all, in which the media has taken great interest and about which Jennifer couldn't care less. Nihilism is her new schtick, and Cody's: Juno's grating patois exists here in lesser concentration, and even then only to reinforce Jennifer's cruelty. ("Boooo, cross out Needy...")

To that end, Cody and Kusama gleefully harvest and collapse horror tropes by the fistful. They have perfect partners in Fox and Seyfried, whose searing chemistry is exploited via everything from a lesbian kiss (from which the suspicious Needy tears herself away, screaming, "What the fuck is happening?") to the requisite, aforementioned girl-home-alone sequence. Yet the principals sell both acts because they submit wholly to Fox. Her Jennifer is is magnetic enough to command irrationality, especially after her demonic conversion, when her physical survival -- not just her social survival -- depends on the sexual compulsions of others.

And to that end, no horror film I've ever seen deconstructs teen sex as adventurously as Jennifer's Body does. Jennifer lures a grieving football player to the woods for what he thinks is a bit of catharsis-by-tryst; it's really just another feast -- his punishment for cheapening the rectitude of mourning. She uses what she understands -- or at least what she understands works -- to literally establish and affirm (and reaffirm) her place in the food chain. Later, when Jennifer's hungry once more, she coaxes a goth kid to a new housing development where she'll rip him to shreds. "I need you frightened," she says. "I need you hopeless." Kusama intercuts the sequence with another of Needy and Chip in the tender throes of their first sexual interlude, which Needy's blood-spattered hallucinations interrupt and ultimately end. ("Am I too big?" Chip asks, delivering Cody's finest bon mot.)

Kusama in particular knows the commodity she has in Fox -- not just gourmet eye-candy that male audiences have binged on through two Transformers films, but a hypermodern symbol of American femininity in all its wily, oppressed and devastating glory. "These are smart bombs," Jennifer insists, grabbing an apprehensive Needy's breasts as they prowl the scene at the rock club. The declamation almost immediately follows admitting the consequences of submission, in this case anal sex ("That hurts!" Jennifer pouts. "I couldn't go to flags the next day, and I had to sit on a bag of frozen peas"). And then, after imposing Jennifer's demonic/animal nature, Kusama and Fox test the male gaze with shocking simplicity: A five-shot sequence of Jennifer swimming nude in a lake, accompanied by throbbing rock music. So unavailable, so deadly, so fucking hot. Hell is a teenage girl.

But not all teenage girls are hell, as Needy's selflessness reveals. But even that doesn't get her very far (Chip will pay the price for that one), soon Seyfried, too, is lost in the darker, abandoned edges of her role, those of a predator without shame or compunction. "Who made who?" Cody asks; Kusama lets the audience draw its own conclusions, even while both overplay their hands with J.K. Simmons and Amy Sedaris as the film's two clueless adults and inconsistent riffs on the cult of celebrity (which, to be fair, already coronated its quintessential demoness in To Die For). But thanks to the shrewd, creative wherewithal of everyone involved -- and even their imperfections, perhaps -- Jennifer's Body bears the mark of an even more fearsome beast: Timelessness.