The shocking true story of a diamond theft gone wrong. In December 1937, four respectable young men in their twenties, all products of elite English public schools, conspired to lure to the luxurious Hyde Park Hotel a representative of Cartier, the renowned jewelry firm. There, the "Mayfair men" brutally bludgeoned diamond salesman Etienne Bellenger and made off with eight rings that today would be worth approximately half a million...