During the war between Wei and Shu, the Shu defeated the Wei using the crossbows they make. In order to attain this powerful weapon, the Wei sent numerous spies to infiltrate the Shu kingdom and steal it. Chen Gong and Xun Xu are Shu spies who have infiltrated Wei kingdom for many years. After knowing the plan of Wei, they decided to work separately to stop it. Chen Gong continued to stay in Wei kingdom, while Xun Xu went back to Shu kingdom to investigate. In the midst of investigation, Xun Xu finds out the thief of the crossbows - Mei Chong. He also discovers a highly skilled spy named Zhu Long who is ambushed in Shu kingdom, who is waiting for the opportunity to initiate the Qing Ping plan. Xun Xu devised a scheme to hook Mei Chong, using it as an opportunity to destroy the spy network in Shu kingdom. Despite eventually capturing Gao Chengtang, a corrupted officer, the real Zhu Long is actually someone else. Chen Gong also ends his spy career in Wei kingdom, and goes back to Shu kingdom. Together, Xun Xu and Cheng Gong investigates the Zhu Long incident and discovers the truth behind the Qing Ping plan. Adapted from novel of the same name by Ma Bo Yong.