She disguised herself as Concubine Jing and entered the palace, only to find that the cause of Concubine Jing's death was strange - she did not die of illness at all, but her heart was broken by someone's internal force. And the prince who commissioned her to kill may be the real murderer.
Breaking the situation: She pretended to have amnesia to deal with the emperor while secretly investigating. She discovered that Concubine Jing was collecting evidence of the prince's rebellion during her lifetime, and that the evidence was hidden somewhere in the palace. She must get them before the prince finds them.