During a visit to a castle, Blöki digs up worn coins from the ground. A neighbor takes over the valuable antique from them, but attributes the price to the family's previous debt. There is no fairy tale, more coins are needed for the desired wealth, but where can they be found? Géza turns to Öcsi, his great-grandson, who uses a time-expanding device to transport the entire family to the 13th century, but one must be careful with the past, and it is good to know history.