Ancient Olympia, 432 BC. The sculptor Phidias is working on completing the enormous chryselephantine statue of Zeus. Working with him in the workshop is Agesilaus, his young nephew. In Agesilaus' company are Teucer, the son of the chief guard of the sanctuary, and their peer, Thalia, the daughter of the city's largest innkeeper.

One night, the two boys secretly enter the temple of Zeus and, well hidden, they accidentally see a strange man stealing gold from the base of the sacred statue. The next day, the temple priests accuse the sculptor Phidias, as his cup, bearing his name, was found at the scene of the theft. From then on, the three friends secretly begin an investigation to uncover the real thief.
Who wanted to incriminate Phidias and why is the smooth conduct of the Olympic Games at risk?