Threshers celebrate good harvest. Boniface, a retired soldier, pays his compliments to maid Rosa, but she doesn’t fancy him. He reminds her in shame that when Kalina proposed to her twenty years ago, her family rejected him because he was poor. Hurt Kalina then married the poorest girl in the village. He accuses Rose of still loving Kalina. Upset Rosa proclaims Kalina as the traitor of their love.
Aldermen come in; a bricklayer master is handing over a new house to Kalina wishing him all the best. Kalina´s and Malina´s supporters meet in the pub where the atmosphere of mutual entanglement gradually grows. A singer Skrivanek comes in and both rivals ask for a song. But eventually it´s lyrics show the true spirit of their problems and help solving them. Malina is moved and willing to reconcile with Kalina. However, he mentions the debt that Kalina has because of his new house and that makes Kalina angry again. Rosa blames Kalina that he didn’t do anything to save their relationship although Friar Barnabas had left him a secret that should reunite them again. Their dispute is interrupted by a song of a piper, who invites other people to come dancing. Angry Kalina crashes the piper to the ground distracting Malina. Only Kalina´s son Vit and Malina´s daughter Blazenka can calm down their fathers and take them home. Then they decide to arrange a secret meeting.
Boniface founds a letter in the fight addressed to Kalina and Kalina founds out that it is the letter from deceased Barnabas and tells Vit and Boniface about the treasure that should stay a secret. Vit and Boniface must promise him that they won’t tell anyone else about it. As soon as they leave, Boniface under the same promise tells the bricklayer master. He then says it to an innkeeper, other neighbours as well as to bellman Jirik.
Vit and Blazenka meet on a bench. Jirka the bellman tells the secret of alderman Kalina to singer Skrivanek, using the speaking trumpet. And then the whole town learns about it.
Kalina comes under Bezdez to seek the treasure. He wonders about his faith, desire for gold and Rosa. Exhausted he falls asleep and dreams about Barnabas, the prater, who is followed by rocky ghosts. They urge him to keep looking for the treasure although he might lose his soul and end up in hell. The ghosts disappear as procession celebrating Virgin Mary approaches him. Kalina wakes up and starts praying.
Vit and Blazenka meet and she wants to keep their love a secret. Vit is of a different opinion and gets upset. Boniface sees them and call on the whole procession to come to them. Everyone learns about the secret young love and fathers reject the happiness of their children after Vit stands up for it. He loves Blazenka and he wants to marry her despite everything. The procession goes away, only Rosa stays deeply touched by Vit´s decision. She thinks about her own life and admits that she still loves Kalina. Boniface surprises her and clumsily expresses his love to her. But Rosa refuses him again. Then they all see Kalina going down under the ground still looking for the treasure. Rosa tries to stop him.
In Malina´s house menials chop the hops. They ask sad Blazenka to sing for them. But she sings a heartbreaking song and bursts to tears. No one can see Blazenka like this so they try to convince Malina to let Vit marry her anyway. In the end, he agrees but under the condition that Kalina comes to beg for his son himself. Boniface says that Kalina can never come, as he is already lost for good. He then tells them all about the treasure secret but they all must promise not to tell anyone about it. Vit comes to say goodbye, before he goes away and hopes to come back in a year with some money to ask Blazenka to marry him again. Malina assures him he will approve of their marriage, but only if Kalina begs him. Boniface as Vit´s uncle wants to step in instead of the father and at the same time he once again asks to marry maid Rosa but he is rejected.
Something starts to bang in the oven, which at first makes everyone laugh, but after a while it becomes frightening so they flee from the house. Only Rosa stays in watching the oven´s door burst out and Kalina coming out. He realizes that the secret of the treasure he looked for was Rosa´s love. Everyone come back to the house. Kalina begs Malina to let Vit marry Blazenka and him marry Rosa. He finally agrees and in the end the victory of great love is celebrated.