Blood Bound (Mercy Thompson, Book 2 of 8) [Audiobook]

Mechanic Mercy Thompson has friends in low places – and in dark ones. And now she owes one of them a favor. Since she can shapeshift at will, she agrees to act as some extra muscle when her vampire friend Stefan goes to deliver a message to another of his kind. But this new vampire is hardly ordinary – and neither is the demon inside of him.