Bone Crossed - Patricia Briggs - paperback

Mercy Thompson, book 4 of 14 ongoing series

As a shapeshifter with some unique talents, ace car mechanic Mercy has had to maintain a tenuous harmony between the human and the not so human within the Tri-Cities of Eastern Washington on more than one occasion. But this time she may be in over her head.

Marsilia, the local Vampire Queen, has learned that Mercy crossed her by slaying a member of her clan. Now she's out for blood. But since Mercy is protected from the vampire's direct reprisal by the werewolf pack, and her close relationship with its sexy Alpha, it's not Mercy's blood Marsilia is after. 

It's her friends.