Althea was once a popular girl with friends, a great skier, and an award winning horseback rider. When she got to high school through, everyone went their separate ways. Despite having a dance and athletic background, she lost a spot on the cheerleading squad to a freshman, Celeste. The ancient evil who lives inside her home offers her a deal: bring him Celeste and he'll make Althea popular.
See, Althea's house has a turret with shutters on the inside and outside of each window. A vampire lives inside that room, and despite being told multiple times not to go inside, she did and met the creature that would change her life. He promises that Celeste will just get tired and that she'll actually be back to school the day after “it” happens. Still not sure what to do, she decides to ingratiate herself into Celeste's life.
Althea suddenly goes to practice and goes out of her way to be friends with the younger girl. At every turn though, she gets shot down. Celeste says she can't come over to her house because she has cheerleading practice, which she says in a snotty kind of way. Althea keeps trying though, which eventually leads to Celeste coming over to her house and Althea suggesting that they check out the shuttered room.
Everything changes the next day at school. Becky, one of the cheerleaders, suddenly acts like her best friend. She invites her to come hang out with the popular crowd at McDonald's, talks to her about school, and pushes her to flirt with this guy Ryan. Ryan is so enamored of Althea that he follows her to class, talks with her about astronomy, and makes it clear that he can't wait to see her at McDonald's later.
At chorus, a bunch of kids make fun of Celeste for showing up looking super tired and pale. Althea is suddenly so popular that she can sit wherever she wants. Despite having a massive crush on Michael, she's more than willing to flirt with Ryan at McDonald's, especially since Michael has his own girlfriend. Nothing much happens over the next few chapters though.
She thinks that she sees the vampire outside in the sun a few times. Becky convinces her to throw a party for the popular kids in her house. Then they get the news that Celeste dropped off the squad. Since high school kids are sheep who go along with the popular kids, when Becky calls Celeste a loser and says she's a quitter, everyone follows along.
Althea makes it on the squad because almost no one else tries out. When the JV squad pitches a fit over not getting to try out, the coach gets super quiet and weird before calming them down. Althea briefly wonders if someone or something forced the coach to choose a new cheerleader instead of someone from the JV squad. She then runs into one of her older friends and graciously invites the girl to her upcoming party.
The vampire then comes to her and tells her that she has to give him one of her party guests. If she doesn't, he'll make her unpopular again. He tells her that she can make her choice known by putting her arm around the person she chooses. Jennie, her former best friend, winds up telling a bunch of stories from when they were younger. They laugh, have fun, and agree to always be friends and never let things get in the way again.
Althea makes the mistake of putting her arm around Jennie though. Freaking out, she runs outside and screams that this wasn't her choice. She smells a dusty or moldy scent and watches in horror as Jennie suddenly gets the urge to go outside. She also sees the vampire's arm reach out for Jennie. The vampire later tells her that he'll wipe the minds of those there to make sure they don't remember her freak out.
Jennie doesn't come to school on Monday and actually doesn't come back to school at all. Everyone pretty much gets over it, and Althea becomes one of the most popular people in school. Even the seniors know her name. Becky suddenly becomes way less popular though. The other girls get really snotty with her and talk about her behind her back.
While at Pizza Hut, Althea sees Becky come in looking super nervous. She invites her to join them at their table. When everyone gets up to leave and ignores her once again, she asks Becky to spend the night that weekend. Michael's girlfriend Constance stops by and hangs out with Althea, Michael, and Ryan. Even though she wants the older girl's boyfriend, Althea is in awe of Constance. By inviting Becky to her house though, she's sealed the poor girl's fate and made the cheerleader the vampire's next victim instead of choosing her competition.
To save Becky, she offers to spend the night at the other girl's house, especially after the vampire demands Becky as his next victim. Becky sets it up so that Ryan can come over to see her. Althea senses the vampire outside and begs Becky to stay in the house, but the girl goes outside the next day. When they wake up the next morning, Becky is so weak that she can't even lift her juice glass. Her mom flips out and seriously considers making her quit the squad because it takes up so much of her life.
This makes Althea rush home and up to the shutter room. When she can't get the windows open to close the exterior shutters, she actually breaks the glass. Before she can close the interior shutters, the vampire shuts the door and starts taking her over. That's when Ryan shows up outside and sees her. He plays his music so loud that she can drown out the vampire's voice insider her head and get outside. They go back to Pizza Hut and find Becky is suddenly all better.
Though she might think that she's safe, the vampire comes back. He says that Becky's house was just a little too far away, which is why he didn't affect her the way he did others. When Althea claims she doesn't need him and will no longer help him, he suggests she go to school the next day without him. It goes about the way you would expect.
First, her car won't start. Then while walking to school, someone splashes mud all over her clothes. No one will talk to her or even acknowledge her. Girls from the JV squad tell her that try outs for the basketball cheerleading squad are coming up and that there's no chance she'll get a spot. Varsity cheerleaders talk about how much she sucked like she's not even there, and even Becky acts like she doesn't exist. Ryan seems to have no interest in her either. She then sees Celeste and Jennie sitting near each other in the cafeteria with a space between them that practically screams out her name.
The vampire agrees to change her life back to the way it was before and even give her back Becky if she agrees to give him Constance. When she goes back to school, everyone loves her again. The captain of the squad gives her a ride, Becky apologizes for being a creep, and Ryan sends her an apology note too. Constance and Michael suggest they go out on a double date. Though Constance seems pretty nice, Althea suggests they hang out at her house and even agrees to let Constance check out the shutter room.
The closer they get to her house though, the more she freaks out. She eventually starts screaming at them to leave and get away from her house. Constance thinks she doesn't like her, and Ryan thinks that she's crazy. He pretty much throws her from the car, makes a few rude comments, and peels out with his friends. Needless to say, the vampire isn't too happy.
Althea begs him to let her be popular just one more time. When he agrees, she fights back. She tells him that he only gets stronger when weak people give in to his demands and take his offers. When she rejects his latest offer, it makes him feel weak and gives her the strength to close all the shutters. Though she lost her old life, she thinks that if she works hard enough, she can get it back. It then ends with the vampire sitting in the shutter room and waiting until his next victim arrives.