The Big Sleep — Raymond Chandler (1939)

Raymond Chandler's debut Philip Marlowe novel established the hardboiled private detective as American literature's defining moral figure — a knight of the mean streets who maintains personal honour in a corrupt world. Chandler's prose style is so distinctive and beautiful that literary critics (including W.H. Auden) have argued it transcends genre entirely. The novel's plot is famously so complex that Chandler himself couldn't explain who killed one of the victims.