Film noir has rules: they’re rules about plot and character; about femmes fatales and doomed guys in fedora hats; about stark lighting that slices up the image into shards of black and white. The genre was a child of war, a cinema of darkness and suspicion suited a Hollywood working under the blackout conditions and power-rationing imposed after Pearl Harbor. Stranger on the Third Floor (1940) is usually held to be the first example (though it took critics in Paris to give the genre its name). After the war, the genre didn’t seem out of touch with a postwar America of disillusioned ex-servicemen who had returned to find that their wives had managed pretty well without them; and a culture ready to listen to the portentous words of Senator McCarthy. The film critic and journalist Matthew Sweet guides you through the rise of Film Noir, and explains how and why it all came to an end in the 1950s, yet somehow the genre retains a little magic that we can't help but hark back to from time to time.