Discworld: Book 8 - Guards! Guards!

'The people next door oppress me all night long. I tell them, I work all day, a man's got to have some time to learn to play the tuba. That's oppression, that is. If I'm not under the heel of the oppressor I don't know who is.'
An aura of mean-minded resentfulness is thick in the streets of Ankh-Morpork. Insurrection is in the air. The Haves and Have-Nots are about to fall out all over again. The Have-Nots ant some of their own magic. But magic in the hands of amateurs is a dangerous thing. The City Watch is the last line of defence against such unnatural goings-on. But when even the Watch have trouble telling Right from Wrong, you know that Law and Order ain't what it used to be. But that's all about to change...