Tapage nocturne (1951)

Armand Varescot, a rich and tyrannical old man, is killed by his young and pretty secretary, Caroline, while he was trying to abuse her. To avoid scandal, his granddaughter Marie Varescot convinces Frank, his cousin, to take responsibility for this "accidental" death, he who is in love with Caroline. But Commissioner Legrand, who has designs on Marie, only agrees to close the affair if Marie marries her, and if Frank leaves with Caroline, abandoning his share of the inheritance. The arrangement is accepted and life goes on.