My upcoming lengthy essay, "Spy Noirs and the Origins of Film Noir," for the anthology, "Light and Shadow" (Alain Silver and James Ursini, editors) has a section, "Spy Noirs Contradict Film Noir’s “Origins Myths,” which I begin as follows:
"For decades, pop culture journalists and ivory tower historians have repeated the same two claims about the origins of film noir. First, its content derives from literature, foremost of which is hardboiled crime fiction. Second, its visual style derives from European émigré film professionals, who drew on their familiarity with expressionism once they were in Hollywood. Spy noirs contribute to exposing both claims as false – as nothing more than myths."
If you're interested, stay tuned.