Paris, November 1940. Lili is seventeen years old. She was carefree before the war but is now driven by circumstance to join the Museum of Man, one of the first Parisian resistance movements, led by ethnologist Boris Vildé. With her new comrades, Jeannot and brothers André and Bernard Kirschen, Lili takes up the fight.
While Lili and her friends from the Museum of Man are printing the second issue of “Resistance” in a clandestine workshop, the Gestapo arrive and take chase. Lili and the Kid, her new colleague and first love, manage to escape and join their leader, Boris. They are in no doubt that they were betrayed by one of their own. Despite efforts to unmask the traitor, the heads of the network fall one by one.
Paris, 1941. Captured by the Gestapo, Boris, the Kid and members of the Museum of Man await their trial. Defeated, Lili joins the Youth Battalion, a group of young resistance fighters led by twenty-one year old communist Fredo. Together, they practice armed fighting and, to avenge the dead, Fredo and his comrades plan the assassination of several German soldiers.
Boris, the Kid and most of the network members were sentenced by a German court and shot. Lili is devastated. She takes refuge in Lyon where she discovers new comrades and a less violent resistance. As part of the Combat network, she transports clandestine newspapers between Lyon and Paris where she continues to fight with the Youth Battalion. Meanwhile, her brothers in arms fall one after the other, including André Kirschen.
February 1943. Bernard Kirschen was shot and André Kirschen was deported. Lili returns to Lyon where she codes messages to London and organises the escape of her friend Victoria. She also manages to identify the traitor responsible for the arrest of her friends from the Museum of Man and, in turn, falls into the hands of the Gestapo.
After a spectacular escape, Lili leaves Lyon and returns to Paris where she learns that a new operation is preparing to free a leader of the Resistance … her own father! While the Allies land in Normandy and the young fighters gather in Paris for their last battles, Lili and Jeannot are arrested.