In ancient Athens, one of the pupils of Plato's Academy is found dead. His idealistic teacher Diagoras is convinced the pupil's death is not as accidental as it appears, and asks the famous Heracles Pontor, the "Decipherer of Enigmas," to investigate. As the death toll rises, the two men find themselves drawn into the dangerous underworld of the Athenian aristocracy, risking their own lives to solve the riddle of these young men's deaths.

Simultaneously, a second plot unfolds: that of the modern-day translator of the ancient text, who, as he proceeds with his work, becomes convinced that the original author has hidden a second meaning in the text, one that can be interpreted through certain repeated words and images. As the story advances, however, the translator is alarmed to discover references to himself, which seem to address him personally in an increasingly menacing fashion.