Gai is a top assassin in Ling'an. In order to avenge his brothers back then, Gai was ordered to go to Beiqi to steal the secret code of the formation. Encountering Ke and Ying on the way, the three of them worked together to try to outwit the letter of the lieutenant general of Kitazaki General Jie. Unexpectedly, Ying had already been bought off, and all this was a big conspiracy. square. Gai, who learned the truth, decided to rescue his comrades, kill his enemies, and eliminate harm for the people.