Su Du finds out that Cheng Qi is the spy and is killed on the spot. Zhan Yan arrives and is arrested for killing Yu Du. Gu Chang and Zhan Yan have a battle. If Zhan Yan wins he wants to tell his side of the story. Zhan Yan loses but Duan Mu doesn't kill him. Zhan Yan tells Duan Mu to find evidence on the body to prove who the killer is. The demon clan learns of the human clan's plans. Zhan Yan arrives in time to save the witnesses. Duan Mu gives Zhan Yan three days to find the murderer. Zhan Yan sets a trap for the spy. (Source: jindreame at MyDramaList)