Arthur Bryant, John May and the Peculiar Crimes Unit are on the trail of an enigma: Mr Fox. His identity is false, and his links to society are invisible. Their search takes them into the vast labyrinth of the Underground, a subterranean world full of legends and ghost stations. Edging closer to what lies beneath the city, are Bryant and May about to uncover something truly bizarre?The most enigmatic detectives in British crime fiction since Holmes and Watson return in their eighth wickedly entertaining and intriguing investigation...