“Jennifer’s Body” is a human-eating, revenge-stricken horror film that seems hungry for the box office. But not even a script written by Diablo Cody (“Juno”) or a long-lasting lip-lock between Megan Fox (“Transformers”) and Amanda Seyfried (“Mama Mia!”) can save this film.

Set in the boondocks of Minnesota, the story revolves around friends Jennifer (Fox) and Needy (Seyfried). Best friends since childhood, Needy is loyal to Jennifer even though they couldn’t seem more different: Needy is a geek and Jennifer is the popular girl at school. As her name implies, Needy is subservient to Jennifer’s manipulative ways, but things are about to change.

In an attempt to make their small town seem more exciting, Jennifer drags Needy to the local bar to see the band Low Shoulder. But the two girls don’t realize what’s in store for them when the bar burns down and the lead singer of the band, played by Adam Brody (“The O.C.”), convinces Jennifer to leave with his band — where she is used as a sacrifice that turns her into a flesh-eating demon.

Jennifer’s appetite can only be quenched through the seduction and consumption of the males at her high school. But when Needy’s boyfriend becomes the victim, she fights back.

Diablo Cody’s second film is a long fall from the well-written (and Academy Award-winning) “Juno.” Cody’s plot never hits ground and doesn’t seem to know when to stop. Jennifer may be hungry for humans but what her diet is truly lacking is a storyline that isn’t scattered about like the inside of her victims.

Also unlike “Juno,” this film doesn’t capture the witty character interactions that made “Juno” famous. Instead, the dialogue is filled with teeny-bopper clich?s that don’t fit the mood of the film. It’s as if Cody was trying to make this an instant cult classic, but tried too hard. “Jennifer’s Body” simply lacks the uniqueness of a cult film.

Director Karyn Kusama (“Girlfight”) uses Fox’s body to attract viewers instead of a well-adjusted plot. Fox’s scenes never gain momentum, and this includes the horror scenes, which come across as dull. In one of the concluding scenes (of which there seems to be about four), Kusama’s lack of direction is evident when one of the most terrifying parts of the film turns into a yearning for a shower instead of fear.

Fox’s performance might have boded well in a pornographic film, but her reliance on her looks is all too obvious in this film. Her boobs seem to have more lines than she does.

Beyond her body, her emotional performance, which should drastically fluctuate between high school hottie and demon-possessed flesh-eater, never seem to waver beyond a flirty smile and a screaming demon.

Seyfried is truly the only quality part of this film. Her role as Needy changes from high school nerd to a revenge-stricken woman, a transition Seyfried handles with ease. You feel for Needy and her struggles, and better still she is the only actress that can deliver a “Diablo Cody” line. It takes a special delivery that manages to be both kitschy and sincere without sounding trite.

The few better parts of the film are mostly based on comedy and not horror. J.K. Simmons’ (“Juno”) hyperbolic portrayal of the emotionally distraught biology teacher is relaxing as comedic relief, as his character is used to express the emotions of the town as Jennifer’s murders continue, but he does so in a tongue-in-cheek manner.

The true downfall of this film seems to be the casting of Fox. Her inability to be anything besides a pinup girl is obvious, and this is only enforced by Kusama’s blatant use of her sexuality. “Jennifer’s Body” turns from a horror film to a whore, leaving Jennifer’s body the only thing to be desired.

1 1/2 stars out of 5