Così Come Sei is a 1978 Italian erotic drama directed by Alberto Lattuada and starring Marcello Mastroianni and a young Nastassja Kinski, in which Giulio — a middle-aged Roman architect unhappily married — travels to Florence for work and falls instantly and passionately in love with Francesca, a beautiful, sexually uninhibited teenage girl. The two begin a consuming affair and spend an intense period locked away together in a Madrid hotel room — until an old friend plants a devastating seed of doubt in Giulio's mind, suggesting that Francesca may actually be his biological daughter from a long-forgotten affair with her mother years ago. Giulio is torn apart by guilt and obsession, unable to resist Francesca despite the looming possibility of incest — and it is ultimately Francesca herself, the younger of the two, who finds the strength to walk away and end it.