Huo Longcheng, the border city guardian defending Juedong Pass, unexpectedly shuttles to modern Jiangcheng. To help his starving companions and common people survive, he carries cement from construction sites and raises food and cold-weather supplies from the metropolis, bringing the convenience of modern life back to the ancient city bit by bit. In cross-border travels again and again, he makes friends with enthusiastic partners such as Su Xiao and A Qiang, and also welcomes external forces closing in step by step and heavy tests within the city. With ancient responsibility colliding with modern wisdom, can Huo Longcheng guard the isolated city and protect the thousands of households?