It is the summer of 1871 when Scotland Yard's Inspector Ben Ross pays a visit to Jacob Jacobus, the old rogue of Limehouse: infamous antiquarian, friend to villains and informer to the police. Ben hopes to glean information about any burglaries that might take place now that the wealthiest echelons of society are back in London for the Season. Little does he realise that an audacious theft has already occurred - a priceless family heirloom, the Roxby emerald necklace, has been stolen from a dressing table in the Roxby residence, and the widowed Mrs Roxby is demanding its immediate return. Ben's day gets worse when he and his wife Lizzie are interrupted that evening by the news that Jacob Jacobus has been found dead in his room with his throat slit from ear to ear ... Surely the two crimes cannot be connected? But with Ben's meticulous investigative skills and Lizzie's relentless curiosity, it is only a matter of time before the tragic truth is revealed.