Warner Bros. was ahead of its time in dealing with the Nazi threat before the U.S. entered World War II. The studio exposed the evils of fascism in A films like Confessions of a Nazi Spy (1939) and B pictures like this fast-paced thriller. Underground didn't set out to be a B picture. The original story--about two German brothers, one a resistance fighter, the other a dedicated soldier for the Reich--came from top screen writers Carl Justus Mayer and Oliver H.P. Garrett, and the role of the soldier brother eventually brought into the Resistance was intended for John Garfield. At some point, however, the film moved to Bryan Foy's B unit, where the leads went to Warner's players Jeffrey Lynn as the young soldier, Kaaren Verne as the resistance member he loves and Phillip Dorn, on loan from MGM, as the brother already broadcasting anti-Nazi messages. Director Vincent Sherman was learning his craft directing B movies at Warner's. After Underground he would graduate to the As with the Humphrey Bogart vehicle All Through the Night (1941), followed by more hits with The Hard Way (1943), Mr. Skeffington (1944) and The Damned Don't Cry (1950).

By Frank Miller