Ross Macdonald’s The Underground Man fits within the sub-genre of the hardboiled detective novel. The protagonist, Lew Archer, has appeared in many of Ross Macdonald’s novels. Archer matches the category of the cynical private investigator—almost always male—who specializes in delving into dark, disturbing mysteries. He tends to operate within an unsavory underworld. As he seeks to uncover the cold, hard facts, this type of detective is countered by a ruthless antagonist. That evil-doer, who may be of any gender, often the perpetrator of violent crimes and may exhibit sadistic tendencies. This violence generally includes one or more murders.
The detective often experiences strong physical attraction to, or may have a sexual relationship with, at least one of the female characters, who may turn out to be the criminal. His lack of faith in human nature and his understanding that he will probably have to turn someone in both serve to keep him out of emotional entanglements.
In The Underground Man, Archer checks many of the boxes of the typical hardboiled detective, but he is somewhat less jaded. He shows empathy for both the victims and the perpetrators, and he sometimes expresses insights into the subtleties and paradoxes of human nature. In the case of the Broadhursts, he is saddened by the wasted lives and potential.