A maimed Nazi soldier comes to learn that his brother is the leader of the underground broadcasts he has been spying against.
In Berlin Eric Franken (Philip Dorn) enters a secret room and tells Alex (Peter Whitney) and others to fix the radio so they can broadcast. Eric goes home and calls violinist Sylvia (Kaaren Verne). At the station Eric greets his brother Kurt Franken (Jeffrey Lynn) and sees he lost his arm as a soldier. Their father Albert (Erwin Kalser) opposes war and argues with Kurt. Gustav Muller asks Albert to help his wife sleep and says his son was killed. Kurt wants to go out and finds Sylvia's name. Eric sneaks out to join Sylvia and others to broadcast for the underground, reporting bombing and the truth. Nazis locate their transmitter; but Fraulein Gessner (Mona Maris) warns them, and they flee as Alex blows up their stalled truck. Sylvia finds Kurt waiting for her at the restaurant where she plays. Col. Heller (Martin Kosleck) to find them sends for radio man Hoffman (Wolfgang Zilzer) from Dachau concentration camp. Eric says they must buy radio equipment, and they vote to take Hoffman back, sending Josef (Henry Brandon) to meet him. Hoffman calls Heller that the underground contacted him. Gessner hears but cannot warn them. Heller arrives with the Gestapo, and Josef is shot as Hoffman comes in. The lights are shut off, and others escape. Hoffman finds Eric and Alex in his room and pleads he gave no names in two years of suffering. Eric and Alex go out and hear the shot.
In church Sylvia is given a baggage ticket, but on the street Kurt joins her. Sylvia says it is not her bag but is arrested with Kurt, who is questioned by Heller. Eric comes in to vouch for Kurt. Heller threatens weary Sylvia, slaps her, and releases her. Kurt is waiting for Sylvia, but she collapses. Eric asks Kurt not to see Sylvia. Heller summons Kurt and shows him the evidence, asking him to spy on Sylvia. Kurt walks home with Sylvia and warns her they are watching her. A package is delivered to Sylvia, and Kurt sees her hide it. After Kurt goes out, Eric comes in and says Kurt knows.
Eric's mother says that Muller was arrested. Eric gets a gun, and Kurt admits he spied for Heller but says he can't report Sylvia. Eric warns him not to see her again. Heller calls Kurt and says they are going to broadcast tonight. Kurt snoops and calls Heller where they are. Kurt takes Sylvia in his car, but she says Eric is there. They hear him on the radio and then the arrests. Kurt goes to Heller and finds a servant is a witness against his father. Gessner learns that Kurt did not know about Eric and takes him to see Albert and Eric being tortured. Gessner asks Kurt to help the underground. Kurt tells Heller he knew about Eric and admits it to Eric. In the final scene Albert and Eric are about to be executed but hear Kurt broadcasting for the underground.
This powerful drama of heroic resistance to Nazi terror
exposed the horrors of Germany under Hitler, and shows that courageous
people can work against that oppression without being violent