Watch on SFlix. The fairy tale is based on two fairy tales by Božena Němcová, "Righteous Bohumil" and "The Black Princess". It tells the story of a weak king and his wife, whose desire for a child leads her to a conspiracy with the devil. The princess, who grows up under the influence of the "impure" powers, only escapes from their power thanks to her love for the fisherman Radek.