Qin Ming, who is good at mecha deception, was recruited by Bai Qi, who was good at solving puzzles, to join the Imperial Guard as a firefighter in the Fire Control Department. During the Fire Lightning case, he met Jing Yifei, the "big sister" of the Military Affairs Department. Together, they form a team of detectives unraveling not only the layers of mist, but also discovering their own origins and the meaning of being part of the Imperial Guards.