Girl with the Golden Panties（1980）

Luys Forest is a writer with a Falangist political past. He lives isolated in a coastal town, writing his memoirs (actually rewriting and adapting his autobiography with the times), and brooding over his failed marriage. His sister is worried about him and decides to send her daughter Mariana to stay with him. Mariana and a seemingly mute and artistic lesbian companion come to town to shake the stable world of Luys with their free and uninhibited ways. Soon begins a game of seduction that ends up exposing the intellectual game of Luys.