It is based on upon the memoir Mémoires d'un agent secret de la France libre et La Ligne de démarcation by Gilbert Renault under his pseudonym Colonel Rémy. A small village in the Jura is split by the river Loue which creates the line of demarcation between Nazi occupied France and freedom. A French officer, Pierre, is released by the Nazi soldiers to find his chateau converted into a German command centre. Whilst he is obliged to co-operate with the enemy, his wife Mary supports the resistance movement and is willing to risk her life for it. The Nazis step up their activity against the resistance, insisting that any who attempt to cross the line of demarcation will be shot. When his wife is arrested, Pierre decides to switch his allegiance.
Jean Seberg
as Mary de Damville
Maurice Ronet
as Pierre, comte de Damville
Daniel Gélin
as Doctor Jacques Lafaye
Reinhard Kolldehoff
as le Major von Pritsch
Mario David
as Urbain
Jean Yanne
as M. Tricot
Jacques Perrin
as Michel
Claude Léveillée
as Duncan Presgrave
Stéphane Audran
as La femme du Dr. Lafaye / Wife
Jean-Louis Maury
as Gestapo Agent
Paul Gégauff
as Gestapo Agent
Pierre Gualdi
as le curé du village
