As the door creaks shut behind them, the siblings are enveloped in darkness, their hearts pounding in sync. The boy's hands tremble as he reaches out, finding his sister's cheek, then trailing down to her neck, her collarbone, her breasts. She gasps at his touch, her body arching into his. Their clothes fall away, forgotten, as they explore each other's bodies with a feverish intensity, their moans echoing in the confined space. They are lost in their own world, their inhibitions shattered, their bodies entwined in a dance as old as time.