The story follows the friendship between Jennifer Check and her best friend, Needy Lesnicky, who live in the small town of Devil’s Kettle. Jennifer is a beautiful and popular cheerleader, while Needy is a more reserved and studious girl.
One night, Jennifer convinces Needy to attend a concert by a rock band called Low Shoulder at a local bar. The band is seeking to sacrifice a virgin to the devil in exchange for fame and fortune. During the concert, a fire breaks out, and chaos ensues. Jennifer is taken by the band, who believe her to be a virgin, and they sacrifice her.
However, it is revealed that Jennifer is not a virgin, and the ritual goes awry, causing her to become possessed by a demonic entity. Jennifer returns to school seemingly unharmed, but she begins to exhibit strange behavior. She becomes ravenous and starts seducing and killing her male classmates, consuming their flesh to sustain herself.
Needy becomes increasingly concerned about Jennifer’s behavior and investigates the truth behind the band Low Shoulder and their connection to Jennifer’s possession. She discovers that the band’s lead singer, Nikolai, made a deal with the devil to achieve fame and used Jennifer as a sacrifice.
Needy confronts Jennifer and attempts to stop her, but Jennifer attacks her. Needy manages to stab Jennifer with a ceremonial knife, temporarily incapacitating her. However, Jennifer survives and continues her killing spree.
In a final showdown, Needy confronts Jennifer at her home. Needy reveals that she has also gained demonic powers after being scratched by Jennifer during their earlier altercation. Needy engages Jennifer in a brutal fight, ultimately impaling her on a set of antlers.
With Jennifer defeated, Needy embraces her newfound powers and sets out to seek revenge against those who have wronged her. The film ends with Needy escaping from a mental institution, setting her sights on Low Shoulder and anyone else who stands in her way.