Poland's war begins with a pincer invasion in September 1939, Nazi Germany from the west and the Soviet Union from the east, and this film picks up the story after the swift military defeat to ask what resistance looked like under a six-year occupation. It traces the underground Home Army as it builds an entire shadow state, running secret schools, courts, and a clandestine press while smuggling intelligence to the Allies and sabotaging German supply lines. Archival footage and photographs from occupied Warsaw and the surrounding countryside sit alongside historians laying out the resistance's structure and its costs, including the brutal reprisals the Germans inflicted on civilians for every act of defiance. The narrative builds toward the Warsaw Uprising of 1944, when the resistance rose openly against the occupiers only to be crushed as the Red Army held back on the opposite bank of the Vistula. The film treats Poland's underground state as one of the most extensive resistance movements of the war, distinct from the better-known Western European campaigns.