On the Dark River

Everyone knows that the Su sisters took completely opposite paths on the day the city was destroyed. My sister Su Wu went north to Cangxue Mountain and forged a silver spear in the blood and fire. She became the "ghost general" who was frightened by the enemy, and was also the last unbroken flag in this turbulent world. My sister Su Ying went south to the royal capital and learned how to pour poison with a smile in Jinxiudui, and became the most useful "beauty blade" in the hands of the enemy King Zuo Xian. In this chaotic world, what will happen to the sisters who are at odds with each other?