The Naughty Ones (1981)

Finch, a photographer, doesn't really make a living from his business. One day, he meets his old classmate Mario, who works for a Senator whose daughter he married, Cléo. But Mario is no longer interested in his wife and he has a secret affair with her younger sister Ariane. Finch takes some pictures and he hopes to blackmail him in order to get money from the Senator. Mario asks Ariane for help. Finch makes Ariane pay, who learns the truth of the situation. To punish Mario, Ariane asks him to teach sexual practices to her friend Julie. The maid also begins to blackmail her boss, Mario. Cléo guesses the truth and asks her husband to fulfill his marital duty. Cornered by the four women, Mario gives up everything. The Senator is re-elected and his daughter congratulates him as she pushes her submissive husband in a wheelchair.