Alex and Noémie would like to have a child. But their plans are turned upside down when Alex's mother, Suzanne, has contracted "semantic dementia", a fatal neurodegenerative disease that affects her behavior.
Willy Vander Brook, a world with Franco-Belgian roots, travels to Paris for an interview. He is welcomed by his childhood friend Serge, an ex pub operator, and his roommate Frank, a fierce supporter of the Walloon independence. When Willy discovers that his candidacy is not accepted because he is Belgian, he and his compatriots decide to take revenge
