Ada Fletcher is twenty-one, keeps a collection of knives in her room, and risks her life on a daily basis, helping refugees from a devastating magical war on her homeworld hide on the low-magic Earth. But when she's taken into custody by the Inter-World Alliance, her unusual magic makes her a prime suspect for a supervisor's suspicious death.

Kay Walker, grandson of the Alliance's founder, expects to spend his first week as an Alliance employee chasing monsters out of the dark Passages between worlds, not solving a murder. But when his supervisor dies in suspicious circumstances, he finds himself in charge of questioning a girl he arrested as a suspect. A girl with secrets that threaten to make both of them into the murderer's next targets.

The last thing Ada wants is to help the infuriating Alliance guard who arrested her, but it soon becomes clear that the Alliance knows too much about Ada's offworld origins. More, in fact, than she knows herself. Now she has to choose between loyalty to her family, and helping the Alliance save the Earth - and the Multiverse - from a deadly enemy.