So Young, So Lovely, So Vicious... (1975)

Young Angela, who tied to her father by morbid affection does not accept that her father, the widower Dr. Batrucci, remarried with Irene. After investigating her past, she learns not only about Irene's lesbian tendencies, but also that her stormy relationship with a female high school teacher led her to commit suicide due to the scandal. She decides to seduce her and they have a lesbian sex which is photographed by Sandro, a gigolo. She uses the photographs to blackmail her, but the matter inevitably ends up getting out of hand.