Hamburg.

Germany, 1923. Workers, called to the struggle by the communist Niels Unger, seize the arsenal and turn every building into a fortress. The social democrat Buk does not fulfill Unger's order to blow up the bridge over the Elbe, so the Reichswehr troops enter the city. A bloody massacre begins. Nils Unger is arrested. Buk, who is associated with the punitive leader Meins, betrays the rebels during interrogations. A trial is scheduled for the rebels. To avoid political publicity during the trial, Nils Unger is declared insane, but manages to escape from the prison hospital. Once again, his call resounds through the streets of Hamburg: "Save your guns!"