The story background of Song of the King is Daxing Dynasty, which does not exist in history, but its environment is somewhat similar to that of the late Tang Dynasty, where the imperial power is controlled by eunuchs and the local ministers are divided into different regimes. Although the imperial power is weak, there are still loyal and patriotic ministers. Former Prime Minister Wang Yang is such a person.

Wang Yang repeatedly refuted eunuch Qiu in the court, so he was hated by Qiu. Xing Wenzong knew that Qiu's wings were growing, and if he didn't cut them, the country would be in danger, so he joined forces with others to launch it? The change of morning dew? I want to take this coup to get rid of Qiu. Unfortunately,? The change of morning dew? It ended in failure, and a number of loyal ministers such as former Prime Minister Wang Yang were hunted down by Qiu.

The change of morning dew? Former Wang Yang knew that things could not be done, so he gave Li Yan an idea in advance: recognize Qiu as the adoptive father, bear the burden of humiliation, and when the time is right, eradicate all eunuchs such as Qiu. At the same time, Wang Yang warned Li Yan to be vigilant and not to trust anyone. Li Yan has great respect for his teacher, so he chose to take the thief as his father and lead others personally? Cleaning? When Qiu killed Wang Yang, Li Yan, a loyal minister, was on the scene, but he could only watch his beloved teacher being killed by a traitor.

In anger, he had to keep a clear head, saved Cheng Ruoyu's sisters with his superb archery, and created the illusion that he was dead. When she grew up, one of the two sisters became Qiu's adopted daughter and kept trying to get revenge; The other one was adopted by Cheng, and this is Cheng Ruoyu. Later, Cheng Ruoyu and Qiu teamed up to cooperate with Li Yan to arrest Qiu and other eunuchs. In the process of eliminating Qiu, Li Yan was walking on thin ice. He listened to the teacher's advice and was wary of everyone. He never trusts anyone except Cheng Ruoyu.

To sum up, Cheng Ruoyu's true identity is the descendant of former Prime Minister Wang Yang, and she and Qiu are sisters.