The popular Moravanka brass band performs at the fair. Vasek Pivoňka, the bandleader of the local brass band Kulatěnky, which broke up, decides to put the band back together. The village musicians are sceptical at first, but later they start rehearsing with vigour. Standa, a Prague resident who is working in a pig farm to cure his nerves, helps them to organise the concert. He really likes Evica Kocourková, but her father keeps an eye on her. Young Šišák tries to charm the teacher Olina. Before the performance can begin, the band must succeed before the cultural committee. However, they fail to do so. The disappointed musicians play for themselves at the station and suddenly they are successful. Standa comes up with an idea how to push Kulatěnka through without the permission of the commission. A concert of Moravanka is being prepared in nearby Nechvalin.

In one royal forest, where coal miner Patočka lives and works, the friendly dragon Mrak settles down. The king's lackeys come across him while hunting and, terrified, go to sell the news to the king. He is currently organizing his daughter Viola's birthday party. The hunters describe the dragon in terrifying colors, and so the king concludes that the dragon will, according to tradition, want the king's daughter. So he announces a reward for killing the dragon, but no one wants to fight him. The only one who applies is the princess's favorite, the lutenist Marian, but the king does not like him, so he throws him out. Her brother Jan wants to save the princess, but the king doesn't want to allow it...