During the war, an Allied flyer forced down behind enemy lines becomes a fugitive, moving at night and fighting for survival. Only a small percentage of these airmen make it across German-occupied France back to England. For the first time, the O.S.S. has made contact with a member of the French Underground, a woman named Annette Jobert. She has previously helped airmen to escape. Lieutenant Fontaine of the O.S.S. is assigned to contact Madam Jobert in Paris and establish an "overground railroad" to help these downed Allied flyers escape occupied France.