It is 1809, and the Austro-Polish War is raging. Returning from a reconnaissance mission, Lieutenant Andrzej Zadora and his squad of lancers stop for a rest in Serock, a small Galician town. They spend the night at the "Pod Gwiazdą" inn, where the innkeeper is the young and beautiful Kasia. A passionate feeling develops between the young people. Soon the soldiers leave, and Prince Józef Poniatowski, commander-in-chief of the army, who is in the area inspecting troops, arrives at the inn...

King Sigismund II Augustus of Poland secretly falls in love with Barbara Radziwiłłówna, a noblewoman of Lithuanian magnate lineage, defying his mother Queen Bona’s plans to wed him to a French princess.