Arnau Estanyol arrives in Barcelona to find a city dominated by the construction of the city's great pridethe cathedral of Santa Maria del Marand by its shame, the deadly Inquisition. As a young man, Arnau joins the powerful guild of stoneworkers and helps to build the church with his own hands, while his best friend and adopted brother Joanet studies to become a priest.
With time, Arnau prospers and falls secretly in love with a forbidden woman. But when he is betrayed and hauled before the Inquisitor, he finds himself face-to-face with Joanet. Will he lose his life just as his beloved Cathedral of the Sea is finally completed, or will his brother save him?