Every other day, Kali D'Angelo is a normal 16-year-old girl. She goes to high school. And then every day in between she's something else entirely...every 24 hours her instincts take over and she becomes a demon hunter with unbeatable urges to kill zombies. The trouble is, while her demon hunting powers appear only every other day; the demons appear every day! When Kali notices a mark on the lower back of a popular girl at school, she knows instantly that the girl is marked for death by one of the creatures. Kali has 24 hours - as a human - to save her.