'London Clay' explores the hidden layers that make up this city. Armed with just his tattered Streetfinder map, Chivers leads his reader down forgotten waterways into abandoned catacombs and buried stations, exploring the nooks and crannies of a forgotten city. His network of journeys combine together to produce a compelling interrogation of London's past. In a route that covers much of his own personal history, this is a bold exploration of the city's secrets and asks us also to consider important questions about its future.