Bone Crossed by Patricia Briggs

Bone Crossed is the fourth book in Patricia Briggs' Mercy Thompson series. In Bone Crossed, a world where "witches, vampires, werewolves, and shape-shifters live beside ordinary people", it takes a very unusual woman to call it home. Mercy Thompson is a car mechanic in Eastern Washington. She is planning to marry alpha werewolf Adam Hauptman when a friend asks her to help fend off a ghost. Mercy leaves town, and leaves Adam to deal with vampire queen Marsilia, who is mad at Mercy. The ghost also is harder to deal with than expected, providing plenty of action and thrills. Mercy also explores her preternatural side. As a shape-shifter with some unusual talents, Mercy's found herself maintaining a tenuous harmony between the human and the not-so- human on more than one occasion. This time she may get more than she bargained for.