Traitement de choc (1973) Alain Jessua

When the executive of the fashion industry Helene Masson is dumped by her lover, she has a midlife crisis and her friend Gerome Savignat advises her to spend vacation in the isolated rejuvenation clinic owned by Dr. Devilers and his partner Dr. Berbard. Helene is welcomed by the happy clients and befriends the Portuguese employee Joao, who is an illegal immigrant, practicing her knowledge in Portuguese language with him. After the first injection of a formula based on animal blood, Helene feels very well, But soon Gerome can not afford to pay the treatment and commits suicide. Then Joao disappears and Dr. Devilers does not allow her to check-out the clinic. Helene goes further in her investigation of the clinic and finds the secret of the rejuvenation formula of Dr. Devilers.