The Discworld Reread: Book 12
Stories are dangerous things. As they flow through the world, they cut their paths into the fabric of reality, each time strengthening its shape. As time passes, it becomes harder and harder for a new story to diverge from the old one. In time, every seventh son of a seventh son will become a hero, and every put-upon stepdaughter will be blessed with a fairy godmother. But surely that’s all right? Fairy godmothers are always good, aren’t they? They make sure the story ends as it’s supposed to. But who says what the end should be? Someone in the exotic city of Genua is twisting reality to make it suit the stories, and the three witches of Lancre aren’t having any of that. Despite their fear of ‘forn parts’, they ride out to put things right.