Jim Butcher's The Dresden Files: Fool Moon #7

A Werewolf war has broken out in Chicago-and everyone of the snarling beasts seems to have it in for Harry! Now, it's the Streetwolves-a lycanthropic biker gang who may just hate Harry enough to draw the wrath of country's most powerful gangster. And the werewolf faction that started the blood-soaked conflict is about to be revealed...