Le galopin (1993)

Victor, an unemployed physicist, is hired to serve at an old champagne manufacturer's house. Old man's obsession with women, especially the one who he loved and then lost during WWII, makes his children afraid to be left out of the will. That's why they are trying to become legal guardians and counting on Victor's help to prove their father's mental condition. Little did they know that Victor has his own game going.