Forest soul Mavka faces an impossible choice between her heart and her duty as guardian to the Heart of the Forest, when she falls in love with the talented young human musician Lukas.

In 1812, during the French period, large parts of Germany are occupied by the troops of Napoleon. Several paramilitary Freikorps units battle the French forces, among them the Black Brunswickers led by the 'Black Duke' Frederick William of Brunswick-Wolfenbüttel. After the War of the Fifth Coalition, the Black Hussars are pursued by Napoleon throughout the country, but frequently take refuge with the noble-minded German people.