Half-vampire, half-fairy Isadora Moon is excited about a visit from her older cousin, Mirabelle, who is half-fairy, half-witch, but when Mirabelle persuades Isadora to take a dragon to school, big trouble is in store.

In order to get the attention of Nia, the girl he likes, eleven-year-old A.J. pretends to be a vampire, unaware that she intends to be a slayer. It's the beginning of the new school year and AJ feels like everyone is changing but him. He hasn't grown or had any exciting summer adventures like his best friends have. He even has the same crush he's harbored for years. So AJ decides to take matters into his own hands. But how could a girl like Nia Winters...