In the heart of medieval Barcelona, from the Great Plague to the Inquisition, Arnau, a young peasant, endures the worst torments and humiliations to become a free man. His extraordinary destiny will make him the hero of a whole people. In the fourteenth century, to the rhythm of the construction of the church Santa María del Mar - masterpiece of Catalan Gothic built "for the people and by the people" in record time (fifty-seven years), Arnau Estanyol tries to conquer his freedom.