High school teacher Jiří is torn from his solitude and everyday life by an unexpected nighttime visit from his beloved younger sister, former seamstress Růžena. She tells her brother that she has run away from her husband Fanda, a textile merchant, because of his greed and vulgarity. However, Jiří later learns from his other sister, Tylda, that Růžena spent a lot of money and left her husband for a dragoon captain. The captain has now rejected his pregnant lover because he is getting married. Disappointed, Růžena believes that her brother has turned away from her because of her lie, and she decides to take a desperate step...