Lang's anti-Nazi propaganda film was inspirated by the actual May, 1942 assassination of Reinhard Heydrich. Franz Svoboda (Donlevy) is the member of the Czech resistance who assassinates Heydrich. The Nazis seek revenge and begin rounding up and executing Czech citizens, aided by the traitorous Emil (Lockhart). Franz wants to give himself up to prevent further slaughter but is persuaded to turn the tables on Emil and make him appear to be the assassin. Bertolt Brecht had a hand in the original screenplay but did not receive screen credit and later said most of his work was cut out.