Jacques Romand is a history teacher who has lost faith in his vocation. One evening, witnessing a shopkeeper attacked by three young robbers, he catches one of the aggressors, Victor, a 14-year-old Roma boy.

Yuri, 16, has lived all his life in Gagarin Towers, a vast red-brick housing project on the outskirts of Paris. He dreams of becoming an astronaut. When plans to demolish Gagarin Towers leak out, Yuri joins the resistance. With his friends Diana and Houssam, he embarks on a mission to save their home, which has become his “starship.”