...the dark and inhumane side of human nature with cynicism and doomed love, emphasizing the brutal, unhealthy, seamy, shadowy, dark and sadistic sides of the human experience. An oppressive atmosphere of menace, pessimism, anxiety, suspicion that anything can go wrong, dingy realism, futility, fatalism, defeat and entrapment.
For examples to inspire look at images by Weegee or Brassai, or any of a number of 1940’s cinematic films noirs.