Il fascino sottile del peccato (1987)

Written & directed by Nini Grassia.

Carlotta (Claudia Cavalcanti), the teenage daughter of Arianna (Alessandra Delli Colli), is bored with her affair with Enrico (Saverio Vallone, son of Raf), who’s her aunt Sonia’s (Danila Trebi) fiance. So she sets her sights on seducing her stepfather Aurelio (Vito Fornari), who’s already involved in numerous non marital affairs. Gustavo (Alfredo Gallo), Carlotta’s younger brother, is a closet homosexual. The object of his desire is the unscrupulous Mario (Antonio Uccella). When Arianna finds out about this, she decides to “sacrifice” herself in an attempt to make a man out of him. Soon Gustavo finds himself trapped in a morbid ménage à trois. Things get completely out of control when Mario taking advantage of Gustavo’s weakness for him forces him to arrange for him to go to bed with Arianna.

With a plot like that, Delli Colli as the ultimate milf, and a director who can easily outdo D’Amato in the sleaze department, you know you’re in for a treat.

AKA The Sweet Charm of Sin