Scott Westerfield has done it again with a fulfilling start to his new series, packed with action and threaded with romance. Although a satisfying independent YA novel, Westerfield makes fairly regular references to his previous series, as this novel features the power dynamics of city rulers in that same engaging dystopian world. Frey's father is a tyrannical leader who kept her, the younger twin, a secret from the world, trained from the age of seven as a killer so she can protect her sister Rafia, who is the heir by twenty-six minutes. Frey frequently refers to herself as a "body double," pretending to be Rafia in public settings where their father does not want to risk the heir. Now Frey is sent into her most dangerous role yet: taking her sister's place as a collateral offering from her father to the rulers of a neighboring city. Skillfully navigating the intricacies of her position, Frey dwells on the relative normalcy of her roles in various situations and decides who she can trust with her most powerful secret: her individuality. As a trained fighter who experiences more than her fair share of action, Frey tries to protect what is important to her as she begins to shed her sister's image and discover who she is as an individual.