Victor et François 1995 on netflix

Victor, an eight-year-old boy, finds himself at the head of a large fortune after the death of his father, Philippe. Hélène, his mother, is courted by Roland, a distant cousin who is trying to rekindle a passion from ten years earlier. Victor is worried, especially since Roland has brought Sandrine, a pretty brunette, with him, and the boy discovers her affair with Roland. When Roland takes over the family business that Philippe used to run, Victor becomes frightened.