In an act of friendship and solidarity between two mining towns in 1929, the locals of Kriwoj Rog, Russia, give their flag as a gift to the locals of Bergstedt, Germany. This quickly takes on a symbolic meaning for the miners in Bergstedt as the Nazi party demands that this Soviet gesture be erased and the flag be replaced with their own. The miner and communist party functionary Otto Brosowski (Erwin Geschonneck) publicly declares it his duty to defend this flag against every danger, and he keeps his promise despite his family being threatened by torment and torture.