In a city overrun by monsters, Kate Harker wants to prove she is as ruthless as her father, but August Flynn just wants to be human. He isn't--he is one of the city's three most powerful monsters, who can steal a soul with a song. Events conspire to throw Kate and August together, the only two who can see both sides of the conflict that could destroy their city, and potentially save it. However, the line between heroes and villains is narrow, and in the end, Kate and August may not be able to tell which they need to be more.