The story of former Hollywood star Grace Kelly's crisis of marriage and identity, during a political dispute between Monaco's Prince Rainier III and France's Charles De Gaulle, and a looming French invasion of Monaco in the early 1960s.

Frédéric is arrested for illicit use of narcotic drugs. In jail, he meets he get up close with various sorts of people among which he looks for a role model as a 18-year-old boy.

Lucien Hastier, known as "Lulu", is a locksmith in La Courneuve and a communist activist. He had never known his parents and had been raised by the public assistance, a notary comes to announce that his father died and left him an extraordinary inheritance: a castle, a title of duke and a royal filiation. But problems arise, the deceased duke has left heavy debts and suitors to the title.