The war will separate the members of the Valon family, two sons Alexandre and Antoine being prisoners, while the youngest Gilbert enters the secret army. Only their sister, Denise, will stay on the farm with her grandfather and grandmother. The Germans invade the free zone.

Alain, a doctor, has had his life turned upside down by a family tragedy. To forget, Alain joins the Foreign Legion. With the support of his captain, he wins the trust of the caïd Ben Hadj, heals and saves the latter's son, and falls in love with Kadidja, whom the caïd has entrusted to his care. Ben Hadj fights against the rebels, but sees his friend Alain die. Kadidja emerges to avenge him.