When a regular patron of a London restaurant abruptly vanishes from his long-standing routine, Hercule Poirot identifies a subtle inconsistency in the man's final meal that suggests a hidden tragedy. Poirot seeks to uncover the identity and fate of the man nicknamed 'Old Father Time,' whose decade-long habit of dining at the same establishment on specific days is broken without explanation. The narrative unfolds through Poirot's keen observation of human behavior and his methodical approach to seemingly trivial details. As he engages with his companion, Bonnington, Poirot navigates the social landscape of the restaurant to piece together the life of a man who remained a stranger to those who served him daily.

This short story is widely regarded as a quintessential example of Christie's ability to transform a minor observation into a compelling mystery. Readers often highlight the cleverness of the central clue, which relies on the specific, mundane details of a restaurant order. The narrative is frequently praised for its concise structure, which allows Poirot to demonstrate his deductive brilliance without the need for an expansive cast of suspects. The story serves as a testament to the author's skill in crafting intrigue from the most ordinary circumstances of daily life.