A GIRL KNOWS captures Sapphire LaPiedra's erotic escape in the sauna, where she's joined by the insatiable Sara Retali. Sapphire, her mind elsewhere, can't resist Sara's advances, surrendering to her kinky fingers and toys. Their horny encounter, filled with sensual moaning and erotic exploration, results in a taboo, sauna-sex climax, leaving Sapphire's boyfriend far from her thoughts.