Jim Butcher's The Dresden Files: Fool Moon #4

He's made himself the enemy of the Chicago PD, the FBI, and a werewolf biker gang. His closest friend no longer trusts him. His one time student is dead - the latest victim of a spree of werewolf killings. Now, Harry finds himself face to face with the man (or beast) who could be behind it all. And the full moon is about to rise...