Jim Butcher's Dresden Files: Fool Moon

Harley MacFinn, cursed to become the legendary loup-garou werewolf under the full moon, has been taken into custody by the Chicago Police. Unfortunately, they do not know he's a werewolf-and the full moon will rise within the hour.

Worse, the cell where he'll be held is on the same floor as the office of Karrin Murphy, one of Harry's dearest friends. Oh, and worse yet, Harry's a fugitive, meaning he'll have to break into Police HQ in order to prevent a bloodbath. Isn't the life of a wizard glamorous?