Crime fiction is one of the most successful genres. Its titles fill bestseller lists around the world and provide hours of pleasure to its many readers – including me, a long-time fan of the form. There are various views about why it is so popular. Many offer a variant of Aristotle’s theory of tragedy, which crime novelist Dorothy L. Sayers explains at some length and with satisfying clarity. Aristotle argued that tragedy allows us to experience pity and terror, leading to emotional catharsis. Sayers observes, rather tongue-in-cheek, that reading crime fiction similarly provides us with a safety valve for our…