Guards! Guards! by Terry Pratchett is about secret order that decides to summon a dragon with magic to terrorize the city of Ankh-Morpork in order to stage their own hero to defeat it and become the next ruler of the city. However their plans go terribly wrong and it's up to the night watch to defeat the dragon and apprehend those responsible for summoning it. I found the book to be rather amusing even if it's not one of my favorites in the Discworld series. I particularly enjoyed the humorous portrayal of secret societies and the larger than life character of Lady Ramkin, noblewoman and dragon expert.