Somewhere in Tunisia, commandos of the First French Army are training, in preparation for the August 1945 landings on the southern coast of France. Lt. Claude Legrand (Georges Marchal), who leads the commando, finds among his men a former resistance fighter, Serge Duhamel (André Valmy), who feels nothing but contempt for the lieutenant. Some years earlier, Lt. Legrand and Duhamel had quarreled over Legrand's wife Simone, who had an affair with Duhamel. The commando training goes on but the grudge between the two men still festers. However, after a dangerous mission in which Lt. Legrand behaves heroically, a mutual esteem is born between the two men and grows with time. The long-awaited day of the landing in Provence arrives. The lieutenant and his former rival are now partners in combat.