Kornel and his friend Max thought these would be the most boring holidays of their lives. However, everything changed with the unexpected visit of Uncle Dionizy, who had learned about a great family treasure. Under the guidance of the boys, the Wanderers Club sets off on a journey full of exciting events and extraordinary characters. Things get complicated when cunning criminals - Dr. Kadryll and his clumsy assistant Wieńczysław - also stumble upon the precious trail. A crazy race against time begins. Such an adventure only happens once in a lifetime!