The engine's hum lulls the passengers into a false sense of security, but the sister and brother are wide awake, their bodies pressed together in the narrow aisle seat. Her breath hitches as he grazes her thigh, his hand "accidentally" finding its way between her legs. She bites her lip, suppressing a moan as he teasingly strokes her through her panties. He's rock hard, his cock straining against his jeans, desperate to feel her wet heat. The plane hits turbulence, and they use it as an excuse to grind against each other, their lustful game of cat and mouse reaching new heights.