Were there such a thing as an average teenager, Katie Danvers would be one. She leads an "average" life, content with her family and the town they just moved to. Unfortunately, there is no such thing as "average", as Katie soon discovers. After a frightening incident on Halloween, a seethe of vampires takes interest in her. After they reveal themselves, they stress that she has no choice but to become a vampire. Although Katie does not resist, she is unsettled by the fact that they will tell her everything but the answer to the most important question: Why?
Katie isn't the only one inconvenienced. Elinor, the impetuous leader of the group, fears losing her recruit if she cannot keep a pack of volatile werewolves in check. Before Katie's training is complete, the wolves make a desperate attempt to save her from "a terrible fate". Meanwhile, the seethe unravels a treacherous plot forming right under their noses. In the end, they wonder if Katie is worth the trouble. On one hand, it may be easier to drop her back into her "average" life. On the other, if they turn her, they may be biting off more than they can chew.