Meanwhile, on the novel scene, until the end of the 1930's the best-selling American author of detective fiction was S. S. Van Dine, whose super-sleuth Philo Vance is among the most thoroughgoing snobs ever to appear in fiction. Van Dine's intricate plots follow the rules of Knox's 'Decalogue' and are played out in aristocratic settings into which the reality of corrupt cops, soup lines, and American hard times never intrudes. The purpose is the puzzle. Even today, literally millions of American readers buy detective fiction principally for the classical game.

In one way or another, the puzzle remains essential to the form, as demonstrated in the variety of mutations the detective story has been generating through the twentieth century. To consider the variations, one must start at the base, with «The Murders in the Rue Morgue.» In this story, Poe gives us the model for the classic detective tale, which is still alive and thriving in various modifications. Chevalier Auguste Dupin, his sleuth, not only is, in my opinion, the first detective of detective fiction, but is white, male, of an 'excellent-indeed illustrious family,' financially independent, and an amateur. The police are inept. The crime was the model for thousands of locked-room murders, done in a setting from which it seems impossible for the killer to escape, and the solution is based on close observation of physical evidence to which the superior 'ratiocination' of Dupin is applied. And, true to Poe's disdain for the notion of democracy and the uncouth labouring class, the principal characters (except the killer) are well-bred folks. In «The Purloined Letter, «Poe produced an even purer model, moving crime into the marble halls of the aristocracy.