Feet of Clay by Terry Pratchett

There’s a werewolf with a pre-lunar tension in Ankh-Morpork and a dwarf with attitude and a golem who’s begun to think for itself. But for Commander Vimes, Head of Ankh-Morpork City Watch, that’s only the start . . .

There’s treason in the air. A crime has happened.

He’s not only got to find out whodunit, but howdunit too. He’s not even sure what they dun. But soon as he knows what the questions are, he’s going to want some answers.