A new threat comes to Washington State's Tri-Cities in Briggs's solid 13th Mercy Thompson urban fantasy (after Smoke Bitten). Secrets come out and tensions rise among the Columbia Basin shape-shifter pack when it is implicated in the disappearance of Wulfe, the vampire who has been stalking shape-shifter mechanic Mercy. Marsilia, the mistress of the local vampire seethe, threatens to end the alliance between vampires and werewolves if the pack can't prove its innocence by finding and returning Wulfe to her. Complication arises when a series of dead bodies turn up throughout the Tri-Cities in murders that mimic the killings featured in a new horror movie and appear to be magic in origin. With the pack in danger and Mercy herself targeted by the murderer, she and her allies race to uncover who--or what--is doing the killings. As they peel back the layers of the mystery, they find themselves enmeshed in a more complex and much older supernatural plot. Briggs does a good job integrating exposition into her story, offering fans a refresher course on the characters and their backstories and even allowing new readers to jump in fairly easily. This keeps the series going strong. (Aug.)