The two older witches from Lancre, Granny Weatherwax and Nanny Ogg, need a new witch to complete their three witch coven, since Margaret is occupied with other things, among them being the Queen of Lancre. But the only person who could be the new maiden witch has left Lancre, gone to Ankh-Morpork, to work at the opera. And there, at the opera something is afoul, somehow the ghost who has haunted peacefully for years now has begun to murder people. And when Granny Weatherwax and Nanny Ogg reach Ankh-Morpork to look out for their possible new witch, they find out that the opera has its own kind of magic and if you want to succeed there, you have to play by its rules.
Pratchett is always good at creating new, memorable characters, but filling the spot of Margaret wasn’t an easy task. But with Agnes he has created a character with whom many people on some level can easily identify with. Like always the plot is enjoyable, action, humor, some subtle and not so subtle thinking about the opera and the people who work there.
I enjoyed especially the reasoning of the evil character at the end, that was hilarious, and so was his end. Also the more serious bits about Granny Weatherwax, how she tries not to become another evil witch, since it’s all too easy to use and fall prey to power, which she has in abundance, or the side story about Nanny Ogg’s receipt book, it’s always astonishing how many things Pratchett packs into one book, and how easily he can shift from serious to humor and back.