Welcome to Guards! Guards!, the eighth book in Terry Pratchett's legendary Discworld series.
Long believed extinct, a superb specimen of draco nobilis ("noble dragon" for those who don't understand italics) has appeared in Discworld's greatest city. Not only does this unwelcome visitor have a nasty habit of charbroiling everything in its path, in rather short order it is crowned King (it is a noble dragon, after all...). How did it get there? How is the Unique and Supreme Lodge of the Elucidated Brethren of the Ebon Night involved? Can the Ankh-Morpork City Watch restore order – and the Patrician of Ankh-Morpork to power?
Magic, mayhem, and a marauding dragon...who could ask for anything more?