Shen Zhiyi, a daughter who once served as a prisoner in the capital and was proficient in the art of torture and imprisonment, became a lowly slave in the palace because of her family's injustice. In a bizarre case of death of a palace maid, she relied on her keen insight to seize a glimmer of hope and was forced to form a "master-servant" with the unpredictable prince Zhao Heng. The two work hand in hand to uncover mysterious cases in the turbulent palaces and halls. And each case is like a butterfly fluttering its wings, eventually leading them to a huge conspiracy to overthrow the dynasty.
