Belgian detective Hercule Poirot decides to conclude his professional career by solving twelve final cases, each meticulously chosen to mirror the mythological labours of Hercules. Poirot faces a variety of criminal enigmas, ranging from petty theft to complex murder, while navigating the constraints of his own self-imposed thematic challenge. He relies on his sharp intellect and the occasional assistance of his loyal staff, Miss Lemon and George, to bring these disparate investigations to a close. The narrative framework consists of twelve distinct short stories, each functioning as a self-contained puzzle that Poirot must resolve before his retirement.

This collection is widely regarded as a clever exercise in structural ingenuity, showcasing Christie's ability to blend classical mythology with the conventions of the detective genre. Readers often appreciate the playful nature of the premise, noting how Poirot's commitment to the theme adds a layer of charm to his final investigations. While some critics point out that the connection between the crimes and the myths varies in strength, the overall consensus highlights the work as a quintessential example of Christie's mastery of the short story form. The book remains a staple for fans of the series, providing a satisfying, if slightly whimsical, conclusion to the detective's active career.