Dana Praeger and her new boyfriend Joey Adams make out in the woods behind a secluded building on campus, when they are startled by the sudden appearance of a classmate, Cheryl Hawkins who seems disoriented, her clothes torn and her body bruised. Cheryl later confides to Dana that she had been taken from her bed, then probed and examined by her abductors. Dana's concern mounts when she notices a symbol has been branded behind Cheryl's right ear. The mysterious abduction of her college classmate prompts Dana to call her father, Matt Praeger, to investigate.
On campus, the OSIR begins to collect details of the strange case. Stone announces that traces of Gamma Hydroxybutyric Acid (GHB) - a date rape drug - were found in Cheryl's urine sample. Hendricks suspects that the symbol branded behind Cheryl's ear appears to have its origins in the occult; Praeger finds evidence of a dark sparkling powder on a piece of Cheryl's torn clothing. The powder turns out to be a bizarre mixture of ingredients - a veritable witches brew.
Meanwhile, it's rush week on campus and Psi Beta Sigma is recruiting new members. Unaware of a more sinister motive, Dana's hopes of joining the prestigious sorority are fueled when she is invited by sorority president, Moira Stratton to attend the house tour.
But things are not as they seem. While Dana is at the sorority house, Praeger searches her room for a book on the occult he had lent her but is shocked to find, instead, a cupboard full of wiccan artifacts. When confronted, Dana admits that she is a witch - but that she practices white - not black - magic. She and her coven want to help Cheryl - not hurt her.
The OSIR begins to uncover disturbing clues indicating satanic cult activity on campus. Donner and Axon discover an old satanic site in the woods behind the dorm. Back in the lab, Donner also finds an illustration of "Astaroth" - a high priestess of female demons who is called to the Earth's surface by cults seeking everlasting perfection. Stone remarks on the similarity to Psi Beta Sigma's creed of Purity.
Stone also tells them that missing persons reports indicate the mysterious disappearance of at least one freshman student each year - and all those occurred on the final night of rush week.
Investigation finally reveals that the symbol branded behind Cheryl's ear is most commonly associated with demonolatry and means 'most pure and chaste' - Cheryl's abductors must have been marking virgins. It turns out that the elite sorority is behind the mysterious events. It is now the final night of rush week and, before the moon rises, they must sacrifice a virgin to Astaroth or fail in their quest for perfection. In the woods, with their victim Joey, in a white hooded robe and tied by the wrists to a tree, the satanic ritual begins. Back at the dorm, Donner and Dana perform their own ceremony and, in an agonizing struggle, Astaroth fights to survive against the power of their white magic. But will their power overcome the demon before the next virgin is sacrificed?