In June 1940, as the Germans approach Paris, widowed school teacher Odile decides to flee south with her children Philippe, 13, and Cathy, 7. But on the overcrowded road, their car is destroyed by a bomb. Hiding in the woods, Odile and her children meet Yvan, a 17-year-old teenager who helps them find shelter for the night.
The following day, Yvan discovers a large abandoned house and convinces the small family to take refuge there. While Philippe sees Yvan as a big brother and Cathy as a substitute for her father who died at the beginning of the war, Odile, who is at first wary, becomes more and more attached to this mysterious, illiterate, but resourceful teen.