In this taboo tale, a rebellious sister and her innocent brother find themselves alone and horny. She starts masturbating, her fingers delving into her wet pussy, while he innocently enters the bathroom, catching her in the act. Arguing ensues, but soon they're negotiating a truce. Naked, she takes in his thick, straight cock, and they decide to masturbate openly in front of each other. However, their newfound intimacy is cut short when someone enters, ending their erotic encounter.