Fool Moon by Jim Butcher

You’d think there’d be a little more action for the only professional wizard listed in the Chicago phone book. But lately, Harry Dresden hasn’t been able to dredge up any kind of work: magical, mundane, or menial.
 
Just when it looks like he can’t afford his next meal, a murder comes along that requires his particular brand of supernatural expertise. There’s a brutally mutilated corpse, and monstrous animal markings at the scene. Not to mention that the killing took place on the night of a full moon. Harry knows exactly where this case is headed. Take three guesses—and the first two don’t count...