Underground is a 1941 American war thriller film directed by Vincent Sherman and starring Jeffrey Lynn, Philip Dorn and Kaaren Verne.

Kurt Franken returns from his time at the front, minus an arm but still the fervent, patriotic Nazi that he was when he left.

His brother, Eric, is high up in the resistance and regularly broadcasts on a secret radio.

Eric eventually runs afoul of the Gestapo and is scheduled for execution.

As he is led to the guillotine, he hears his brother’s voice on loudspeakers positioned through the prison.