The heavy door creaks open, revealing the stern figure of their father. The sisters, clad in modest nightgowns, freeze, their hearts pounding. "Come here," he commands, his voice heavy with unspoken desire. They approach, their eyes downcast, their bodies betraying them with every quivering breath. He unties his robe, revealing his hard, throbbing cock. They exchange a glance, a silent agreement, and begin their penance. The elder one takes him into her mouth, her lips stretching around his thickness, while the younger one watches, her hand inching towards her own aching pussy, ready to sin in her own quiet way.