Blood Bound: Mercy Thompson: Book 2 - Patricia Briggs

Like most people who own their own business, I work long hours that start early in the morning. So when someone calls me in the middle of the night, they'd better be dying ...Mechanic Mercy Thompson is woken at 3am by a vampire calling in a favour. He has to deliver a message to a fellow undead and needs a witness that won't be noticed - and Mercy's shapeshifting abilities make her the perfect candidate. But the assignment turns into a bloodbath and Mercy attracts the attention of not just a powerful vampire, but the even more powerful demon possessing him. She can count on the supernatural community for protection - and alpha werewolf Adam would like her to rely on him in other ways too - but when it comes to being proactive, she's on her own.