November, 1937. Simon Burnstone, the Jewish chairman of Kreutzer's Bank and soon to be new Lord Mayor of London, has pig's blood thrown over him in the capital's Royal Exchange. Reporter Johnny Steadman isn't convinced the attacks are motivated by hatred alone. His investigations take him into the vaults under the City and the secretive world of Hatton Garden, where most of the world's diamonds change hands. Behind these closed doors, Johnny uncovers a scheme so vile it could bring down the government as well as hasten the outbreak of war.