The cramped study room, filled with the scent of old books and new desires, becomes their playground. The sister, a virgin, tentatively reaches out to touch her brother's hardness through his pants. He gasps, his cock twitching at her innocent touch. She looks up at him, her eyes wide with curiosity and lust. He guides her hand, teaching her how to stroke him. Their bodies press together, their breaths ragged, as they explore each other's taboo pleasures, the sound of their wet kisses echoing in the silent room.