Hidden in the cloistered confines of their father's study, sisters Clara and Catherine succumb to their secret yearning. Catherine, her lithe body trembling, guides her brother's massive, untouched cock into her hungry mouth. Clara watches, then joins in, their tongues licking, their hands stroking. They move to the floor, Catherine straddling her brother, her tight pussy sliding down his length. They fuck slowly, their bodies entwined, their moans muffled, until they reach a shared, shuddering climax, their bodies slick with sweat and spent fluids.