Ruehlmann, who becomes more and more shocked by the brutal murder that most modern fictional detectives claim as their righteous tool, looks to the beginnings of the genre to find how today's crime novel got so bloody. Private eyes have not all been armed messiahs; some, like Poe's Dupin, or Sherlock Holmes, were mental wizards and fathered a school of aesthete-intellectual riddle stories that held sway for 60 years. Then came Dashiell Hammett and the hardboiled, hard-mouthed private eye whose idea of culture and brilliance is a double Scotch and the coldblooded completion of ""the job."" In the Depression the job is paramount, and has stayed that way. But Hammett is also a poetic stylist and Ruehlmann may well spark renewed interest in him; he quotes Hammett to wonderful effect. Also surveyed are Raymond Chandler's Philip Marlowe, lapsed Jehovah's Witness Mickey Spillane's paranoids, Ross Macdonald's compassionate Lew Archer (the detectives' whole careers are studied), and today's superavengers bellydeep in gore and numb parody -- Ruehlmann's views are hardly new (nor does his title really fit his thesis) but his book is hypnotically readable -- kill after kill.