Using restored, colorized archives and testimonies from all the players in this conflict, this documentary covers the hundred days of apocalyptic fighting that wrote History. June 1944, the Allies landed in Normandy. This odyssey was meticulously prepared for months. The construction of two artificial ports, the transport of Anglo-American troops, their training cost colossal efforts, and caused many cold sweats: the secret of D-Day almost came to light several times. The documentary reveals the inner workings of Operation Overlord, it also deciphers the military operations, and evokes the choices of the high command. Placed at human level, it retraces the fate of Norman civilians subjected to deadly bombings, the attitude of the Allied soldiers and their German adversaries, as well as the aspirations of the French population, torn between fear and hope.