"Un Lun Dun" is a young adult novel by British author China Miéville. The book is set in the city of London, but in an alternative universe known as UnLondon. The story follows the adventures of two girls, Zanna and Deeba, who discover a hidden world beneath the streets of London. UnLondon is a place where discarded objects and ideas from the "real" London end up, creating a surreal and unpredictable landscape. As the girls explore this strange world, they encounter a cast of eccentric characters, including a talking book, a half-ghost boy, and a group of sentient garbage bins. The girls soon discover that they have a crucial role to play in a battle between good and evil that is unfolding in UnLondon. The book is a thrilling and imaginative adventure that explores themes of identity, power, and the importance of standing up for what is right. With its vivid descriptions and richly imagined world, "Un Lun Dun" is sure to captivate readers of all ages.