Cab driver Francis "Chas" Chandler leads an unremarkable existence. His greatest moments have come tagging along with John Constantine—as a chauffeur. His home life is nothing special, and his beloved London is becoming a soulless metropolis. In middle age, Chas is stuck in a rut. But Chas is a master of "The Knowledge," the elaborate system of routes and landmarks which every London cabbie must memorize. Until now, The Knowledge has been just a tool for Chas. But now, he is about to discover a more sinister significance of The Knowledge.