Humans need fantasy to be human. To be the place where the falling angel meets the rising ape.
Short version: the Hog Father (twisted Santa Clause) is missing, extra belief is sloshing about causing all sorts of trouble, and Death has stepped up to fill the roll.
New character: Mister Teatime (it’s pronounced Teh-ah-tim-eh). He’s an assassin that has been hired by the Auditors to remove the Hog Father and is entirely too good at his job in an odd, laterally thinking sort of way. He’s interesting enough, but the repetitions of the correct pronunciation go from funny to old fairly quickly.
Susan is back and continuing to try very hard to be normal, despite a tendency to remember things that haven’t happened yet and occasionally SPEAK IN ALL CAPS. She’s a lovely character and really drives the story, even more than Death.
The Wizards are back as something of a sideplot, but more interestingly is their thinking machine Hex. I’ve always liked the analogue to actual modern computers of a seemingly magic collection of random pieces that don’t make sense to the layperson and yet can somehow answer complicated questions. Long term storage is bees? Of course it is. Try to remove the mouse’s cheese and it won’t work anymore? Yup. Great fun.
Overall, it’s a wonderful exploration of belief with all the zaniness Discworld has in the best of times. Well worth the read.