Nikolaï was abandoned at birth and has been in foster care ever since. Although a family would like to give the sixteen-year-old boy a home, he decides to make one himself. He meets Camille, an intriguing fifteen-year-old wiseacre, and tries to convince her to make a child together. Nikolaï is convinced that he can handle any problem and wants to avoid at all costs that an adult thwarts his plans. Camille and Nikolaï flee together from the home and isolate themselves in the woods. In the heart of this gloomy, mysterious forest, Nikolaï will have to face his first feelings and learn to become a man. Soon, he feels that there are many things he cannot control.

After the accidental death of his son on a racetrack, Edward Milan, a wealthy industrialist, asks his nephew to find his grandson, who has been living in an orphanage for eleven years and whose existence he has just learned. But the boy, named Martineau, is suspicious of the police since he has been unjustly accused of shoplifting. He runs away when the two uniforms in charge of taking him back to his grandfather's house appear. He manages to find lodging with an old lady, a kleptomaniac at times, then with a theater prop master who is persecuted by his fiancée and finally with a lonely veterinarian.

The zone interdite refers to two distinct territories established in German-occupied France during the Second World War after the signature of the Second Armistice at Compiègne.