The film is based on Russian heroic legends and folklore. In a tall mansion, the beautiful Marya Morevna is waiting for her bridegroom, the mighty warrior Nikita Kozhemyaka. The longed-for meeting may happen any minute, but all of a sudden the Russian land is invaded by the armies of Kashchei the Immortal that bring destruction and death. Marya Morevna is abducted, and Nikita Kozhemyaka finds just ashes on the site of his home. But thanks to a kindly wizard who gave him a cap of darkness, the hero will find a way to rescue his bride and rout Kashchei.