Suspicion rises in the quiet little village of Belder when a strange horse back rider arrives in town: Jan Stephorst. In Greece, he was called Zeppos, has inherited the beautiful Belderbos castle. He was offered a huge amount of money for the castle, but he declines the offer and starts an investigation on his own to try and find out who is behind the offer. Together with Ben Kurrel and Rita Mees, a student and a baker's daughter, he discovers that the organisation of Baral (with the help of Zeppos' niece Ariane Despinal) is trying to gain possession of the valuable oil reserves underneath the Belderbos estate.
—Anonymous