Unknown (libro en Inglés) - Rachel Caine

Second in the new series from the New York Times bestselling author Living among mortals, the djinn Cassiel has developed a reluctant affection for them-especially for Warden Luis Rocha. As the mystery deepens around the kidnapping of innocent Warden children, Cassiel and Luis are the only ones who can investigate both the human and djinn realms. But the trail will lead them to a traitor who may be more powerful than they can handle...