When the estranged wife of Lord Edgware publicly declares her intent to eliminate him, his subsequent murder places her at the center of a seemingly impossible investigation. Hercule Poirot must navigate a web of conflicting testimonies and a seemingly airtight alibi to uncover the truth behind the nobleman's death. The narrative follows the classic detective framework, utilizing Captain Hastings as the observant foil to Poirot's methodical, psychological approach to deduction. As the investigation deepens, Poirot faces the challenge of reconciling the physical evidence of the crime with the social performance of the primary suspect.

This novel is widely regarded as a quintessential example of Christie's mastery of the intricate puzzle mystery. Critics and readers alike have long praised the narrative for its clever manipulation of the reader's perception and its tight, logical construction. The case is frequently cited as a highlight of the Poirot series, showcasing the detective's unique ability to look past surface-level appearances to the underlying truth. The enduring appeal of the work lies in its balance of character-driven drama and the rigorous, almost mathematical precision of the central mystery.