There has been an uneasy peace between mortals and the Fey since the latter retreated to live on reservations such as the one near Mercy Thompson Hauptman's home in Washington State. In the course of stopping an attacking troll released from the Walla Walla reservation, coyote shifter Mercy and her alpha werewolf husband, Adam, meet Aiden, a changeling held for years by the Fey. Old friend Zee convinces Mercy and the pack to protect Aiden, putting the clan at odds with not only the powerful Grey Lords but also the Marrock, leader of all North American werewolves. Mercy continues to struggle for her place among the werewolves as a conflict between Fey and mortals appears to be inevitable.