A reconstruction of the events of the "Bloody Sunday" in Bydgoszcz in September 1939. The action of the movie begins on August 31, 1939. The film tells the story of the heroic defense of the Poles, accompanied by the tragic love story of a German woman, Anna-Maria, and a Pole, Piotr. Due to their romantic relationship, the characters suffer a lot of persecution. Piotr dies at the hands of pro-German militants, who then massacre the inhabitants of Bydgoszcz.