Still reeling from having lost her chance to become a vampire, sixteen-year-old Rayne learns that she is destined to be the new Vampire Slayer and must go undercover to stop a maniacal member of the undead who seeks vengeance and power by spreading a fatal blood disease.
Rayne McDonald, a goth vampire and vampire slayer, must go undercover as a cheerleader at her high school to find out what happened to the captain of the football team, who has disappeared, and to see if the peppy cheerleaders are really werewolves.
Sunny and her twin sister Rayne travel to Las Vegas, where Sunny's boyfriend Magnus, the leader of the Blood Coven, is attending a vampire convention where he will take a beautiful female as his blood mate.
After learning that their ex-hippie parents are actually fairies, vampire Rayne and her twin sister Sunny are forced to hide out in a secluded Swiss boarding school for vampire slayers that, the twins discover, is hiding some secrets of its own.
When Rayne is chosen to track down her twin sister, Sunny, and Sunny's vampire boyfriend, Magnus, for what will mean certain death at the hands of the Vampire Consortium, she and her boyfriend Jareth go deep beneath New York City and through the Gates of the Underworld in hopes of saving them.
After making a deal with the devil, Rayne and her twin sister Sunny have been given the chance to go back in time to prevent that fateful night when Sunny was bitten by vampire Magnus from ever happening.