During the Shaoxing period of the Southern Song Dynasty, four years after Hero Yue Fei's death, Qin Hui led his troops to negotiate with the Kingdom of Jin. On the eve of the meeting, the envoy of the Kingdom of Jin died at the prime minister's residence, and the secret letter he was carrying disappeared. By chance, a small soldier and the deputy commander of the personal battalion were involved in this huge conspiracy. Prime Minister Qin Hui ordered the two to find the murderer within an hour, but things were far from that simple... With the in-depth investigation full of dangers, the truth behind the case seems to be a bigger conspiracy hidden.