The detective’s name Poirot—Hercule (Hercules)—comes from the name of the ancient Greek hero Heracles (Hercules). And even though the little mustachioed Belgian doesn’t look like the mythological giant, the detective has to carry out deeds no less great. In the collection “The Labors of Hercules,” each of the twelve novellas about Hercule Poirot’s investigations echoes a corresponding labor of Hercules.