He has been called a genius and a fraud, a hero and an addict. He advised kings in their glittering palaces, then disappeared into the darkest alleys of London's criminal underworld. He was (and remains) a global icon, but he could pass his most ardent fan on the street without a flicker of recognition. Who was this Sherlock Holmes? Nick Rennison gathers the clues of a life lived among the stars of the late nineteenth and early twentieth centuries,...