Dai Geyong, an overworked corporate employee, unexpectedly travels back to the Ming Dynasty during the Tumu Crisis. Faced with an imminent catastrophe, he refuses to back down. Armed with his extensive knowledge of Ming history and a burning sense of patriotism, he joins the battle to defend the capital. Standing alongside Yu Qian, he reorganizes the army and coordinates food and supplies using modern management strategies. By combining knowledge with practical action, he fights to protect the city's people amid the flames of war. This is not one man's legend, but a two-way journey across time. When modern ingenuity meets ancient loyalty and courage, what stands firm beneath the artillery fire is not only the people's spirit, but the unbreakable backbone of the Ming Dynasty.