A bored, horny sister and brother find themselves alone together, their curiosity piqued. She retreats to her room, fingers her wet pussy under the covers, trying to suppress her moans. He, too, begins to stroke his growing cock in the bathroom. Their shared arousal is palpable, and when he catches her in the act, they can't help but engage in a heated argument that quickly escalates into mutual masturbation. Naked and exposed, they fantasize about each other, their inhibitions crumbling.