Since Cao Cao release Sima Yi from the cell, Cao Cao took Sima Yi and given him an order to be his assistant. And so, Cao Cao order Sima Yi to lecture his Son, Cao Xiong, to gain knowledge and experience in strategist.
In the middle of the journey, Cao Cao and Sima Yi is in the same carriage. Cao Cao is resting in deep headache while Sima Yi hear his last words. Cao Cao, look alike dead infront of Sima Yi, he's full of panic and command everyone to stop the journey, Sima Yi immediately call the medical staff for the inspections. As Sima Yi enter the carriage, Cao Cao wasn't really inside, Cao Cao was taken a pee for awhile. In Cao Cao's mind, he was trying to test Sima Yi's loyalty.
Xun Yu received that Cao Cao will return to his base as written in the date. Xun Yu emerge told Cao Pi and the brothers to stay inside the stronghold to prevent from any bloodshed, and Xun Yu knows that it might be a thread if Cao Cao returns from the war. Xun Yu and Cao Cao predicted, that Han Sui and Ma Teng will assassinate Cao Cao from the north gate.
The days to await Cao Cao has come, Cao Pi, Xun Yu, and the Minister held the North Gate for Cao Cao's carriage to enter. The assassin suddenly appears, Cao Cao is shot by the arrow, aim to his chest. Xun Yu command the army to protect Cao Cao and assault the assassins. Cao Pi carry his father, and Xun Yu find out that it was a decoy. The Imposter Cao Cao tells them that the real Cao Cao was enter the West Gate.