Measure for Measure (1943)

a duke who is about to undertake a long journey entrusts his cousin with the regency of his duchy. he who, apparently, is a rigid and intransigent champion of the law, turns out to be instead a wicked power-hungry, blackmailing the girl loved by the young duke and, in order to enslave her to his pleasure, he bargains with her the freedom of his brother accused of conspiracy and sentenced to death. but the return of the duke puts everything back in place and the dishonest cousin will have the punishment he deserves.