The sudden reappearance of a notorious criminal in a fog-shrouded London forces Albert Campion into a high-stakes pursuit to prevent further violence. Campion must navigate the labyrinthine streets and the psychological complexity of Jack Havoc, a charismatic and dangerous fugitive who operates outside the bounds of conventional morality. The narrative follows Campion as he attempts to anticipate the movements of a man who thrives in the chaos of the city's smog. The story utilizes a third-person perspective to contrast the methodical nature of the detective against the unpredictable volatility of the antagonist.

Readers frequently highlight the atmospheric quality of the writing, noting how the London fog serves as a central character in the narrative. Discussion often centers on the complex portrayal of Jack Havoc, who is frequently cited as one of the more compelling antagonists in the genre. Critics often point to the balance between Campion's understated intelligence and the visceral threat posed by the fugitive. The pacing is generally described as deliberate, allowing for a deep exploration of the moral questions raised by the conflict. Many readers appreciate the way the book moves beyond simple procedural elements to examine the nature of criminality and redemption.