In the dim light of the closet, the sisters' breaths mingle as they hover on the precipice of sin. Their hearts race, pounding against their chests like drums heralding their downfall. The older sister's fingers trace the younger's lips, parting them gently, as the younger's hands find their way under her sister's habit, caressing the soft skin of her thighs. They whimper and moan softly, their bodies pressed together, their hips grinding in a rhythm as old as time. As their fingers delve deeper, their breaths come in short gasps, their bodies tensing and arching as they reach the peak of their forbidden pleasure.