Carpe Jugulum
Terry Pratchett
Granny Weatherwax falters
Queen Magrat has given birth to a daughter. There is to be a ceremony to name her, and King Verence has invited practically everyone. Wanting to be a thoroughly modern monarch who is not bound by old prejudices, he has even invited a family of vampyres from Uberwald, led by the Count de Magpyr. This is a foolish and dangerous thing to do. But it's the kind of thing Verence, with the best of intentions, is always doing.
Ordinarily we would expect Granny Weatherwax to be on top of a potential problem like this. But Granny is getting old, and she makes two serious mistakes (which I will reveal only in spoiler tags). [spoiler1] Although Verence and Magrat invite her to the naming, sending an invitation decorated with gold leaf, and even ask her to be the baby's godmother, Granny doesn't receive an invitation to the naming ceremony. [spoiler2]
Thus, the most powerful witch in Lancre believes that she had not been invited to the naming ceremony. Well, of course this is a familiar story from folk tales. In the classic tales the powerful witch shows up at the ceremony and curses the child. I got that far in my thoughts, then said to myself, "That's not gonna happen. Granny is incapable of intentionally harming a child."
It's a great setup. And Carpe Jugulum is, in my opinion, one of the best novels in Terry Pratchett's Discworld series. Pratchett is always a vivid stylist with a sense of humor that beats everyone. He also manages sometimes, but not always, to tell a good, exciting story. Carpe Jugulum is such a one.
First mistake -- she fails to detect that a family of vampyres has entered Lancre.
Magpies, being attracted to shiny tat, and perhaps also under the influence of Clan Magpyre, steal the invitation. Granny fails to realize this. Nanny and Agnes figure out what happened.