In the district of Lukovo, Yan Skshetuski is living with his wife and her adopted father, Zagloba. Stanislaw Skshetuski, Yan's cousin, announces the treachery and all three decide to make for Prince Radzivill's palace at Kyedani via Upita to see Michal Volodyovski. They learn that Pan Gosyevski and Yudytski have been arrested. They are summoned to a private meeting with the Prince who then meets two Swedish envoys (Count Lowenhaupt and Baron Schitte). Before a feast that evening, Kmita is summoned by the Prince and made to swear on the holy cross that he will not leave him until death. Olenka and Kmita are reunited and make peace. The Prince announces his alliance with the Swedes and the Skshetuskis and Zagloba are thrown into prison for dissent. Radzivill explains his thinking to Kmita who decides to remain loyal.