Between June 1940 and March 1943, the 1200 kilometer long demarcation line split France in two. For almost three years, she ordered the daily newspaper of 40 million French people. To the north, the zone occupied by Hitler's soldiers, to the south, the zone administered by the Vichy regime of Marshal Pétain. This film lifts the veil on this theater of the shameful mistakes of collaboration as that of the most courageous and noble acts. Archive footage and footage from locations once crossed by the line are interspersed with interviews with the last witnesses of that era. Sons and daughters of smugglers tell how they helped their parents risk their lives to smuggle the line to escaped soldiers, downed airmen or entire families on the run.