A policeman is discovered murdered in a clockmaker's residence with a steel clock hand embedded in his neck, initiating a complex investigation for Dr. Gideon Fell. Dr. Fell must navigate a series of bizarre occurrences, including a mysterious figure traversing London rooftops, to identify a killer hiding in plain sight. The narrative follows a traditional detective framework, utilizing the logical deduction of the protagonist to dismantle a series of seemingly impossible events. The story is constrained by the atmospheric tension of the clockmaker's house and the frantic pace of the urban setting.

Readers frequently highlight the atmospheric quality of the setting, noting how the clockmaker's house contributes to the overall sense of unease. Discussion often centers on the ingenuity of the murder method and the effectiveness of the locked-room puzzle presented by Carr. Critics often point to the balance between the macabre elements and the intellectual rigor of Dr. Fell's investigative process. Many fans of the genre appreciate the intricate plotting that characterizes this specific entry in the series. The narrative is widely regarded as a quintessential example of the Golden Age detective style, emphasizing puzzle-solving over character-driven drama.