A war hero, invalided home from Afghanistan, meets a strange but charismatic genius who is looking for a flatmate; it is London, 2010, and Dr Watson and Sherlock Holmes are meeting for the first time. A string of impossible suicides has Scotland Yard baffled - and only one man can help.

A mysterious cipher is being scrawled on the walls around London. The first person to see the cipher is dead within hours of reading it. Sherlock plunges into a world of codes and symbols, consulting with London's best graffiti artists. He soon learns that the city is in the grip a gang of international smugglers, a secret society called the Black Lotus.