British pilot Jimmy Porter (Alfred Lynch) crashes his aeroplane in occupied France and immediately finds himself on the run from the Nazis. He meets a young girl, Nina (Cyd Hayman), a part-Jewish agent with important information, and vows to get her back to Britain. He is helped by another agent, code-named Vincent, (Peter Barkworth) and pursued across France by S.S. Officer Lutzig (Philip Madoc), and the ambivalent Abwehr Sgt. Gratz (Robert Hardy), a complex psychological character who is implied to fall in love with Nina. Unlike most previous war dramas, the Nazis were presented as more than just fanatical thugs.