Ethan Morgan is a geeky freshman, not trusted by his parents to stay home alone with his little sister Jane. They hire Erica, a girl from Ethan's high school who is a huge fan of "Dusk" a parody of Twilight, as a babysitter. However, Erica comes across her best friend Sarah and Jesse, Sarah's vampire ex-boyfriend, on the night she is to babysit, and decides to attend a party that Jesse is throwing instead. During a fight between Sarah and Jesse, Sarah ends up at Ethan's house and tells Ethan's parents that she was asked to babysit instead. Ethan suddenly has a vision when touching Sarah, and notices she has no reflection in the mirror, leaving him suspicious of her. He confides this in his dorky best friend, Benny (Atticus Mitchell).
Sarah leaves to get Erica back from the party, knowing the party is full of bloodthirsty vampires. Curious, the boys have Benny's grandmother watch over Jane while they follow Sarah. They see her feed on a rat and realize she is a vampire. Sarah quickly explains that she is only a fledgling, a vampire who has not drunk human blood. The three of them return home, where they are attacked by a vampire sent by Jesse. The vampire is subdued by Sarah and they head to the vampire party to save Erica and their dimwitted friend, Rory. However, Erica has been bitten by Gord and later bites Rory. Ethan, Benny, and Sarah then battle the vampires and escape.
The next day, Rory, now a full vampire after drinking human blood, informs Ethan and Benny that Jesse's gang are going to church so Ethan, Benny, and Sarah follow them. Ethan has a vision in which he sees a gravestone, whose dates unscramble to the number 219, and a mysterious box, which is then uncovered by the vampires. The box is called the Cubile Animus or "Nest of Souls." Ethan and Sarah figure out Jesse's full plan from an old book, learning that in the original settlement of the town, there was a person who went by the name and title of Reverend Horace Black, who led an evil cabal of vampires. During a lunar eclipse, the townspeople burned all the members, leading to all '219' of their deaths. In another vision, Ethan sees that Jesse is, in fact, Horace Black, and plans to use the box to trap the souls of teens going to see the premiere of the new Dusk movie so he can resurrect the souls of his ancient group during the lunar eclipse occurring on the same night.
Benny's grandmother, who reveals that she is an Earth Priestess, gives Ethan, Benny and Sarah enchanted daggers and a spellbook to defeat the vampires. She explains that Ethan sees visions because he is a Seer, which enables him to see visions through touch, and that Benny is a spellmaster, allowing him to cast spells. At the theater, the vampires begin to steal the souls of the teens, but are thwarted by Ethan, Benny and Sarah. Jesse escapes and Ethan and Benny follow in pursuit. In another vision, Ethan sees the tree he saw inside the old book, realizing it's the tree in his backyard, where they find Jesse. As the eclipse begins, Jesse attempts to hold Ethan and Benny down and resurrect the souls he already obtained from the Cubile Animus, but Sarah intervenes. When the box lands in Ethan's hands, he releases the vengeful souls that were captured, which destroy Jesse and return to their bodies.
The next day, Ethan, Benny and Sarah head to school, meeting Erica and Rory, who have decided to live peacefully as vampires.