Hard-boiled popular fiction gave film noir its narrative models, major themes, and verbal style. The genre is commonly associated with the detective fiction of writers like Dashiell Hammett (1894–1961) and Raymond Chandler (1888–1959), which first appeared in the 1920s and provided an alternative to the then-dominant British detective fiction of writers like Sir Arthur Conan Doyle, Dorothy Sayers, and Agatha Christie. The British model presumes a benign society into which crime erupts as an aberration: once a detective has solved the crime, society returns to tranquility. Hard-boiled fiction, to the contrary, presumes a corrupt world in which crime is an everyday occurrence. Its characters are often driven by destructive urges that they can neither understand nor control. Although a detective may solve the story's motivating crime, he entertains no illusions that this small victory makes the world a better place. One narrative model that film noir draws from such fiction implicates the detective when the crime he attempts to solve unexpectedly draws him into its consequences. He often becomes ensnared by a femme fatale or gets set up as the "fall guy" for a larger crime. Nearly everyone with whom he deals is duplicitous. Hard-boiled fiction was not limited to detective fiction; Cornell Woolrich's (1903–1968) Phantom Lady and James M. Cain's (1892–1977) Double Indemnity and The Postman Always Rings Twice share this perspective on life and provided sources for important films noirs .
Hard-boiled fiction—particularly the first-person narration of Chandler's novels—introduced a cynical, doomed, and grimly poetic tone. Its verbal style is apparent in both the wisecracks of the detective and in the moody, voice-over narration dominating many of the films.
German expressionist cinema gave film noir a mood, a visual style, and some themes. A cinema obsessed with madness, loneliness, and the perils of a barely coherent world, it emerged after Germany's devastating defeat in World War I and reflected the despair of the times. Its first major film was Das Kabinett des Doktor Caligari ( The Cabinet of Dr. Caligari, 1920). Nearly everything in it is highly stylized, particularly the set design, which appears to be part of a demented dream, not unlike the despairing mood of many noirs .
By the mid-1920s, expressionism had become a widely respected style, imitated by Hollywood directors like John Ford (1894–1973), and by the 1930s, many expressionist directors and technicians had emigrated to Hollywood, influencing its emergent horror genre directly. A decade later, film noir applied these same tropes of madness, despair, and disorientation to the world of "normal," middle-class experience.
A sophisticated use of the sound track was a defining innovation of film noir, drawing upon techniques developed in American network radio. Network radio and sound film both began in the late 1920s, and by the 1940s, they enjoyed great success. It was not until then that Hollywood learned to use soundtracks in genuinely complex ways, rather than simply as adjuncts to image tracks. By then, network radio had developed writers, technicians, and actors skilled at presenting stories using sound alone; its popularity had accustomed listening audiences to understand complex layerings of sound. Radio narration went beyond linear, retrospective storytelling and employed dynamic interactions between narrating voices ("It all began last Tuesday when …") and dramatic ones ("Who's there?"). Sometimes the same voice narrated and participated in the dramatic action—a common trope in films noirs , which used sound to present two versions of a single character simultaneously. The narrator's voice-over in Double Indemnity , for example, appears throughout the film, telling us his story at a time when he already knows he is doomed; he also speaks throughout the flashback scenes. We hear both his depressed narrating voice and his optimistic younger self, which has not yet learned what both narrator and viewer already know—that his scheme will fail. The aural and visual contrast between his optimistic self and the somber, despairing tone of his narrating self create complex layers of character.
Postwar disillusionment gave film noir a mood and a social context. Victory in World War II did not bring the peacetime happiness that many had anticipated. Films like The Blue Dahlia (1946) show wartime veterans feeling isolated after they return. This disillusionment is also evident in non- noir films of the era, such as that Christmas perennial, It's a Wonderful Life (1947), in which the ugly side of small town America drives a decent businessman to near-suicide. Its miraculously happy ending does not entirely erase the sinister darkness that its portrait of small town life creates.
Disillusionment came from many directions. Women, who had been encouraged to join the work force during the war, now felt pressured to leave it to make room for returning veterans. Labor unions, many of which had been forbidden to strike during the war, now demanded long-awaited benefits. The defeat of the Axis powers did not bring about international security, because the Cold War emerged, generating anxiety about Communist infiltration.
Technological advances made during the war allowed postwar filmmakers greater freedom from the confines of studios. Film stocks were improved, enabling cinematographers to capture a wider range of light than previously possible and, at the same time, to need less in the way of bulky lights; sound recording equipment, particularly improvements in the wire recorder, became more portable; lighter cameras with better lenses became available. Although traditionally composed films had always used location shooting, it had been cumbersome and expensive. Now these technological developments dovetailed with a public taste for "realism" in films and with critical respect for Italian neorealism, a new style from Italy that explored the unvarnished realities of contemporary life. In the United States, Louis de Rochemont (1899–1978), who had produced the March of Time newsreels, produced films such as The House on 92nd Street (1945), Boomerang (1947), and Walk East on Beacon (1952), which used a newsreel aesthetic. These films, and others like them, deal with a world of crime and betrayal, subversion, and people on the edge. Many have been called films noirs , but they look and feel differently from films noirs like Double Indemnity or Scarlet Street . They have a strong narrating presence, but instead of the tormented voice-overs of films like Double Indemnity or Out of the Past (1947), they often employ an authoritative "Voice of God" narrator associated with a governmental institution, such as the FBI or the Treasury Department. They have a very different look from the expressionistic films mentioned earlier, although some of their scenes do have a dark look. They often advertised themselves as "real" or "true," or "pulled from the headlines." The House on 92nd Street prides itself on including "actual FBI" surveillance footage. These films mark the first major reinvention of film noir .
Clearly, the term film noir casts a wide net and has meant different things at different times. Certain images, narrative structures, character types, and themes are widely perceived as typifying it, however. Standard perceptions of film noir include atmospheric black-and-white films from the 1940s and 1950s with specific character types, such as a hard-boiled detective, a femme fatale , a middle-class man in a doomed affair, a rootless drifter, a slick underworld night-club owner; narrative patterns, such as an adulterous couple whose murderous plot leads to their doom, a prosperous, middle-class life unraveling into death or madness, a detective investigating a mystery that turns on him, a drifter or criminal seeking a quick score and then drawn into murder and catastrophe, a couple on the run; iconic images and settings (desolate, nocturnal, urban streets; brightly lit, art-deco nightclubs; mysterious, darkened rooms lit through Venetian blinds); shadowy shots of someone watching from a hidden place; iconic performers (wisecracking, trench-coated Humphrey Bogart; desperate, embittered Dick Powell; terrified, or arrogant, Barbara Stanwyck; sultry Lauren Bacall; Veronica Lake peering through her eye-shrouding hair; arrogant, smug Clifton Webb or George Macready; Robert Mitchum looking grimly resigned or dreamily indifferent; Dana Andrews methodically puzzling out a mystery). The overall atmosphere is one in which something—everything—has gone terribly wrong, a world heavy with doom, paranoia justified and closing in.