In mid-17th century Catalonia, in a climate of crisis and political and social decline, the silversmith from Barcelona, ​​Bernat Ros, moves to Montseny to look for amethysts. His contact with nature and the people of the barony of Taradell and Viladrau, especially with the enigmatic Elda, immerses him in a world of superstitions and hidden powers that lead him to a descent into the world of witchcraft and forbidden knowledge. The apparent placidity of the barony hides a diabolical background and the constant presence of storm clouds in the minds of the people threaten to explode with unknown violence.