During the Napoleanic Wars, members of the Prussian Lützow Free Corps steal a French war chest from the house of collaborator Kerstinn, but their captain Friesen is captured and sentenced to death. But Friesen is saved by French Sergeant Fleuron and they flee the occupied city together. Kerstinn's daughter Marie is disgusted by her father's disloyalty and has also fallen in love with Friesen. When she learns about a trap that is being set for Lützow Free Corps, she sets out to warn them with the help of her father's clerk Püttchen, a Lützow sympathizer.