Chu Zhi and Ouyang Yongxian conspired with each other to start the coup!
One was the sickly third prince. The other was a good-for-nothing crown prince. On the Da Chu side, this conspiracy was only known to Chu Zhi. He pretended to be weak and ill in order to train himself and secretly contact Ouyang Yongxian.
As for Da Yang's side, there were Ouyang Yongxian, Empress Wang, and the Wang family who knew. Originally, Ouyang Hongxian only knew that the people from Da Chu were communicating with someone from the Wang family. He did not know which of the influential people within the Wang family was the traitor, and that had led to him giving the mission to Ouyang Feilong, ultimately resulting in him being injured and meeting Bai Yu for the first time that night.
Bai He had chased Da Chu’s men until he met Bai Yu at the riverbank, where the poisoned corpse, the source of the plague in the village, was found. At that time, no one knew which side those Da Chu’s men were on.