Hidden away in the tiny closet, the siblings' breaths mingle, their hearts pounding with a shared secret. The girl's eyes dart to her brother's crotch, where a noticeable bulge tents his pants. She licks her lips, her own body responding to the forbidden sight. He swallows hard, his eyes never leaving hers as she reaches out, slowly, tentatively, her fingers brushing against the fabric covering his erection. He sucks in a sharp breath, his body tensing. They're teetering on the edge of sin, but the pull is too strong. Their hands roam, exploring, learning, as their breaths grow ragged and their bodies flush with heat.