Lt Glasenapp (Hans Conried) commits suicide at a club which leads the Gestapo to arrest everyone who is present. It gives them an excuse to execute the 26 Czech citizens that they now have in custody under the pretext of the murder of Glasenapp. Unknowingly, they have arrested the leader of the resistance (William Bendix) posing as a washroom attendant. A group of resistance fighters, led by Maria (Katina Paxinou), need contact with Bendix to establish the time to blow up a German ammunition supply and so devise a plan to rescue the prisoners. Also amongst the prisoners is Pressinger (Oskar Homolka) who is Czechoslovakia's most wealthy Nazi sympathiser. His daughter, Milada (Luise Rainer) and her boyfriend Jan (Roland Varno) try to secure his release with the help of Paul Breda (Arturo de Cordova), pitting their wits against Reinhardt (Paul Lukas), the Gestapo Commissioner ...... There are some twists along the way ..... the citizens are to be executed in 72 hours.