Hidden in their cramped attic, brother and sister, both curious and horny, can't resist the urge to explore each other. The sister, a busty brunette, starts by teasingly caressing her brother's chest, moving lower until she reaches his throbbing erection. He, in turn, can't help but grope her full breasts, feeling her nipples harden. They exchange passionate kisses, their bodies pressing together, as they succumb to their taboo desires, their moans echoing in the dimly lit room.