Lulu, roi de France.

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.