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.

The return of Moriarty. The crime of the century. Can Sherlock possibly survive?

Sherlock faces his biggest challenge of all – delivering a Best Man’s speech on John’s wedding day! But all isn’t quite as it seems. Mortal danger stalks the reception – and someone might not make it to the happy couple’s first dance. Sherlock must thank the bridesmaids, solve the case and stop a killer.