A dark and beguiling tour through the streets of a magical London by the Sunday Times bestselling master of modern fantasy, Alan Moore The year is 1949, the city London. Dennis Knuckleyard is a hapless eighteen-year-old who works and lives in a second-hand bookstore. One day, on an errand to retrieve rare books, Dennis discovers that one of them does not exist. It is a fictitious book, yet it is physically there in his hands nonetheless. How? It comes from the Great When, a dark and magical version of the city that is beyond time. There, epochs blend and realities and unrealities blur. If Dennis does not take this book back to the other London, he will be killed.