Why do we take pleasure in gruesome death, neatly packaged as a puzzle to which we may find a satisfactory solution through clues – or if we are not clever enough, have it revealed by the all-powerful tale-teller at the end of the book? It is something to do with being reduced to, and comforted by, playing by the rules. Rules are essential in the classic detective story. In 1929 Ronald Knox drew up the Solemn Oath of the Detection Club. His injunctions included mentioning the criminal in the first five chapters, not revealing the criminal’s thoughts, making sure that the detective – and his “Watson” – revealed all their clues, and not making the detective the criminal.
Three of the Queens of Crime – Dorothy Sayers, Margery Allingham and Ngaio Marsh – also seem to have felt that the form demanded that the detective should be an aristocratic younger son, disdaining a life of leisure in order to use his good mind and fine moral sense.
more from The Telegraph here.