"But, it's not the whole truth.
Tang Yueshan also said that he was drugged before he attacked Tang Ming, and advised him to see a doctor promptly.
At the time, he was completely confused and didn't understand why Tang Yueshan said that.
Tang Yueshan further mentioned that Tang Ming didn't do it knowingly, as he was also drugged, expressing hope that neither of them would be used as a pawn by the schemer behind the scenes and end up becoming enemies.
He clearly understood what kind of person Tang Ming was; Ming certainly wasn't drugged.
It was not until his return journey that he gradually understood that his sister must have tricked Tang Yueshan in some way.
About the assassin, Gu Jiao came to find Gu Changqing. She asked him to set fire to the punishment room and create the illusion of escape, luring the assassin to make a move and frame him.