Welcome to the city of Las Vegas, planet: Earth! Miss Faragonda has sent our four girls to investigate some strange reports and rumors that have been going around; the main one of a vampire hiding amongst the humans.
Miss Faragonda hasn't received enough information to tell whom the vampire-in-disguise, but she was gotten hold of the name of a boy who thinks he might know who the vampire is. The boys name is Charley Brewster, and she asks the girls to look for him.
She has also warned them of the powers these dangerous creatures could have. She needs the girls to try and stop this monster before things get too out of hand, and try seeking out the help of any human "expert" of vampires in the area.