A horny teen sister, home alone with her brother, can't concentrate on her studies. She's distracted by his growing bulge and her own throbbing clit. She starts touching herself, then invites him to join, offering to teach him about pleasure. He resists at first, but her wet, eager pussy and skilled hands soon change his mind. They fuck hard and raw, their taboo lust consuming them, until they're left panting and guilty, wondering if they've gone too far.