Het Verraad Van De Zwarte Roofridder(1962)

Johan, Hilde, Alwin, and Robert are walking through the forest. Suddenly, they see a man being beaten up by a few knights. They rush to the man's aid and chase the knights away. The man, named Casper, introduces himself and says that Knight Koen sent him. He has a message for Knight Bruno. The four take Casper to Bruno's castle, where he tells Knight Bruno his message: the green seal has disappeared. It has been stolen, and they suspect the black knight. Johan and Alwin set off together to retrieve the seal. But is Casper telling the truth? And was he really sent by Knight Koen?