Six renowned crime writers of the 1930s attempt to construct the perfect, unsolvable murder, pitting their fictional ingenuity against the real-world investigative expertise of Scotland Yard Superintendent Cornish. Each author crafts a distinct narrative designed to bypass standard police procedure and forensic detection methods of the era. The collection functions as a meta-fictional battle of wits, where the narrative framework alternates between the creative execution of a crime and the analytical critique provided by a seasoned law enforcement professional. The protagonists in these stories operate within the rigid social and logical constraints of interwar Britain, while the Superintendent serves as the final arbiter of their success or failure.

This anthology is regarded as a significant artifact of the Golden Age of detective fiction, highlighting the playful yet rigorous intellectual culture of the Detection Club. Readers and critics often note that the value of the work lies less in the individual stories themselves and more in the fascinating interplay between the authors' creative malice and the Superintendent's pragmatic, procedural responses. The inclusion of Christie's essay provides a rare glimpse into the era's obsession with real-life unsolved crimes, grounding the fictional exercises in historical reality. The collection serves as a testament to the technical proficiency of these authors, who sought to push the boundaries of the genre by testing the limits of contemporary investigative logic.