The period of the classic American detective stories, especially the hard boiled ones. The classic era of Film Noir. War may be happening in Europe, but for the moment it's still the Jazz Age in the USA. Newspapers are sold by young, possibly disabled, boys on the street. Businesses are run by Corrupt Corporate Executives, and while the well-off enjoy nightclubs, the after-effects of The Great Depression still overshadow the lives of the poor. Everyone wears hats.