In the Middle Ages, a famous artist, accompanied by his young apprentice, returns to the village where his celebrity all began 30 years earlier. At that time, he had represented the figure of Christ in mosaic, the first in a long series, an image whose beauty and purity enabled the church, still in its infancy, to evangelize the entire country. But the old man has a secret: this face of Christ, so holy and merciful, was born neither from his imagination nor from some mystic inspiration – it originated from an imperfect model, a human model, and from a Machiavellian pact forever linking the destinies of two men.