For most kids, catching fireflies is a fun summer activity. For twelve-year-old Serwa Boateng, it's a matter of life and death. That's because Serwa, a Slayer, and knows that some fireflies are really adze, shapeshifting vampires from the forests of Southeastern Ghana. When an adze infiltrates her school, it’s up to her to whip some of her classmates into fighting shape before they all become firefly food. And when she uncovers a secret that upends everything she thought she knew about her family, Serwa will have to decide which side of herself—normal girl or Slayer—is the right one.