Le fiacre 13 (1948)

To secure her fortune with Monsieur Vaudieu de la Tour, the Machiavellian Claudia kills her lover's elder brother and steals his child. The boy is adopted by a coachman, and later, as secretary to the Minister of Justice, discovers the truth, punishes the bad guys, rewards the good ones and marries the daughter of another innocent man, unjustly accused by Claudia.