The Green Seal, a magical item, has been stolen by the Black Knight. The seal belongs to knight Bruno and must be found soon, otherwise power over the country will fall into the hands of someone else. Alwin, Bruno's eldest son, pursues the black knight with his page Johan, but is ambushed and imprisoned. His younger brother Roberte and his sister Hilde decide to go after him, when they find the castle of the black knight they free Alwin and steal the seal.