L'arc de Cupidon (1970)

Becky, a Scotland Yard inspector, grew up with his aunt and uncle, Heather and Stewart Moore. Becky, who knew from the beginning that his biological mother was the sister of Heather, belatedly discovers the real name of his father, Charles Archibald. She then blames his uncle for having concealed this information and decides to investigate to find the real causes of the death of his mother.