Cathedral of the Sea follows the fortunes of the Estanyol family, from their peasant roots to a son, Arnau, who flees the land only to realize spectacular wealth and devastating problems.
During Arnau's lifetime Barcelona becomes a city of light and darkness, dominated by the construction of the city's great pride -- the cathedral of Santa Maria del Mar -- and by its shame, the deadly Inquisition.
As a young man, Arnau joins the powerful guild of stone-workers and helps to build the church with his own hands, while his best friend and adopted brother Joan studies to become a priest.
When Arnau, who secretly loves a forbidden Jewish woman named Mar, is betrayed and hauled before the Inquisitor, he finds himself face-to-face with his own brother. Will he lose his life just as his beloved Cathedral of the Sea is finally completed?