While his best friend and adopted brother Joan studies to become a priest, young Arnau becomes a member of the guild of the stone-workers, soldier and moneychanger. A strenuous life which leads him from the misery of the fugitive to nobility and wealth. But with this privileged position he also gets the envy of his peers, who devise a sordid plot that puts his life in the hands of the Inquisition. 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?