It is 1914 and Lloyd Osbourne is in London to be married. Arthur Conan Doyle tells him at the wedding reception that he needs a Watson to help him solve the murder of a policeman in Sussex. In the course of their investigation, Doyle brings Osbourne into a world of spies, = codes and other murders. In Lonson they meet P.G> Wodehouse, Somerset Maugham, George Bernard Shaw and the shadow of Oscar Wilde. And Winston Churchill introduces them to C - the mysterious figure who invented the modern British spy network.