In a small, stuffy Brazilian apartment, siblings Paulo and Maria find themselves alone, the tension palpable. Maria, bursting with unspent passion, begins to touch herself, her fingers tracing the curves of her body. Paulo, overhearing her quiet moans, enters the room, catching a glimpse of her naked form. They argue, but the underlying desire is undeniable. Later, they yield to their forbidden urges, Maria's eyes widening at the sight of Paulo's throbbing erection. She fantasizes about feeling it inside her, but their moment is cut short by an unexpected intrusion.