Occupied Paris, 1942. In the dark, treacherous city, the German occupying forces are everywhere - and so are French resistance fighters, working secretly to defeat Hitler. Just before he dies, a man being chased by the Gestapo hands off a strange-looking document to the unsuspecting novelist Paul Ricard. It looks like a blueprint of a part for a military weapon - one that might have important information for the Allied forces - and Ricard realises he must try to get it into the hands of members of the resistance network.