An American traveling in Europe suddenly disappears, and his daughter, married to an eminent scientist, receives a letter asking her to go to Antwerp, which she does with her young son. Both are about to disappear. OSS 117 is asked by his superiors to solve these mysterious disappearances.

During World War II, two French civilians and a downed British Bomber Crew set out from Paris to cross the demarcation line between Nazi-occupied Northern France and the South. From there they will be able to escape to England. First, they must avoid German troops – and the consequences of their own blunders.