Rule One—Nothing is right, nothing is wrong. Kit looks like your average seventeen-year-old high school student, but she has a secret—she's London's notorious "Perfect Killer." She chooses who to murder based on letters left in a secret mailbox, and she's good—no, perfect—at what she does.
Her moral nihilism—the fact that she doesn't believe in right and wrong—makes being a serial killer a whole lot easier . . . until she breaks her own rules by befriending someone she's supposed to murder, as well as the detective in charge of the Perfect Killer case.