When private investigator Lemmy Caution accepts a routine missing person case, he is thrust into a lethal labyrinth of post-war criminal intrigue. Caution operates as a cynical, hard-drinking operative who relies on his fists and quick-fire dialogue to survive the hostile environment of London's underworld. He faces a series of duplicitous informants and dangerous femme fatales who actively obstruct his investigation. The narrative is delivered through a gritty, first-person perspective that emphasizes the protagonist's internal monologue and his cynical worldview.

This work is widely regarded as a quintessential example of the hardboiled detective genre, reflecting the stylistic hallmarks of Peter Cheyney's prolific career. The narrative structure relies heavily on the cynical, wisecracking voice of Lemmy Caution, which serves to define the tone of the entire series. Readers often note the rapid pacing and the author's ability to maintain tension through constant, high-stakes encounters. The book functions as a period piece that captures the specific anxieties and social shifts of the post-war era through the lens of pulp fiction.