The tenth Discworld. Kinda stand-alone. The Unseen University and the Patrician feature in ways to that connect to earlier stories, but the main characters and their tale stand-alone. Those who read the series will see him forcibly adjusting the world-building because he didn't really like the set-up he had given it at first.
But an old man dies and realizes too late that he had not trained a successor to continue lighting the ritual fire. And things start to happen as not quite real things seep into Discworld in search of more reality. Alchemists get the idea for octo-celluose and so for moving pictures. Victor, a student at the Unseen University who has managed to years to do just well enough to stay in the university (according to the terms of his uncle's will) but never actually become a wizard, is infected and so are many others. Around the place where the fire had burned, a ramshackle town -- Holy Wood -- springs up and starts to shoot. C.M.O.T. Dibbler takes over a studio for more dramatic and entertaining pieces than its founder, who found it all educational, and gets started on his epic of love in a world gone mad: Blown Away. Victor gets hired to act and finds with his co-star Ginger they are the worst paid people on the set -- until they discover their star power.
Meanwhile a scruffy little dog has learned to talk.
This involves a stupid but good-looking dog Laddie, a troll named Detritus trying to woo Ruby when Holy Wood and human influence has changed her notion of a proper courtship, Dibbler annoyed that tehy do not have sound when Victor and Ginger improv the perfect dialog under the influence of the Holy Wood, an underground cinema, the Librarian being safe reading a book of nightmares because all its effects are on men, not orangutans.