Bi-curious siblings, bored and horny, find themselves alone in the house, their lust turning to each other. The brother, his cock hard and aching, confesses his desire for his sister's tight, virgin pussy. She, equally aroused, admits her curiosity about his thick, uncut cock. They start tentatively, their hands exploring each other's bodies, but soon, their inhibitions fade. He fingers her wet, tight cunt, while she strokes his massive cock. They're about to go all the way when their mother walks in, catching them in the act.