At a dinner party a guest compares the labours of Poirot to those of the Greek hero Hercules. Poirot has already decided to retire, but first he will take on twelve remarkable cases in the contemporary world that correspond to the twelve labours of Hercules: The Nemean Lion, The Lernean Hydra, The Arcadian Deer, The Erymanthian Boar, The Augean Stables, The Stymphalean Birds, The Cretan Bull, The Horses of Diomedes, The Girdle of Hyppolita, The Flock of Geryon, The Apples of the Hesperides, and The Capture of Cerberus.