In 1648 a Cossack rebellion in the Ukraine threatens the sovereignty of the Polish-Lithuanian Commonwealth over the Cossack nation. The Cossack rebellion also known as the Khmelnytsky Uprising is pitting the Cossack nation and its Crimean Tatar allies against the forces sent by the Polish king John II Casimir. Polish Colonel Michal Wolodyjowski is leading a squadron of Polish cavalry.Traitors,assassins and spies are everywhere. Against the backdrop of the uprising, a Polish knight Skrzetuski and a Cossack leader Bohun fall in love with the same young beautiful woman, Helena. Their rivalry becomes the symbol of Polish-Ukrainian struggle.