Charlotte Castang is a working-class 13-year-old girl, who lives in a drab, run-down neighbourhood, and is ready to become an adult. Her mother died giving birth to her, and she lives with her crass brother and a father whose attention is elsewhere. Her only friend is Lulu, a sick 10-year-old she regards as a pest. Charlotte is antisocial, bored and dreams of a better life. Her life improves when she meets Clara Bauman, a pianist prodigy.

Ariane and Hugo decide to exchange the lives they lead to escape from their routine, which after ten years of marriage, gives them the feeling of being hamsters in a wheel. She suddenly finds herself at the head of a construction equipment rental company and he tries to take the role of a house calling jewelry salesman...But is life really better when you live it on the other side of the bed?