A sorcerer-turned-vampire wreaks havoc on Washington's Tri-Cities, causing death, destruction and a paranormal faceoff in the second of Briggs's series featuring Mercy Thompson, a mechanic and ""walker"": one who can turn into a coyote at will. After attempts by the paranormal community to destroy the malevolent sorcerer fail, Mercy finds herself pulled into the fray: though her werewolf and vampire friends are stronger than she, it turns out that Mercy's abilities make her the only one in town who can save them all. While she discovers the truth about her powers, she also learns more about her past, and the werewolves who raised her. Though the romantic subplot-involving two rival werewolves, Alpha wolf Adam and Mercy's roommate Samuel-fizzles, Briggs has a refreshing knack for imbuing her characters (even non-humans) with lived-in human qualities. When it gets going, this paranormal adventure story is engaging, but a flabby first-person narrative stunts the suspense.