Blue City is Macdonald's first novel in the hard-boiled style andconcerned with a returning soldier who searches out his father's killers and in the process discovers the corruption and violence of postwar urban life.

Macdonald wrote in 1971 that the novel dealt with the "underlife" of an American city. Among the themes the book deals with are such issues as the relationship between political corruption and organized crime and the social effects such a combination has on the atmosphere of the city. By extension, it is also a novel about the moral foundation of the modern world, particularly the questions raised within a democratic society when the price of governance is purchased through the acceptance of an immoral and corrupt underpinning.