Xuanye, a top modern civil engineer, was a lowly craftsman who passed through the Yongqingdu City due to a tunnel collapse. As soon as he woke up, he was attacked by barbarian vanguards. Relying on his professional knowledge, he used yellow mud mixed with lime to reinforce the weak points of the city wall, designed traps overnight to repel the enemy troops, and accidentally rescued the kidnapped daughter of the guilty minister, Wan Li. Xuanye took "building the city to protect the people" as an opportunity, and was appreciated by the guard general, and gradually broke through the restriction of low status. He improved brick-making techniques to build city defenses, dug canals to relieve floods, and even developed trebuchets and improvised explosives to defend against foreign enemies. However, he was involved in the struggle for imperial power - the Duke of Zhenguo wanted to seize his skills, and the Chief of Ceremonies wanted to remove his wings. While Xuanye united the people with his infrastructure strength, he joined forces with Wanli to make plans, taking advantage of the conflict between the vassal king and the barbarians to balance the court. Finally, with a defense system like the "Great Wall", he established the northern border, supported the emperor to ascend the throne, and realized the legend of "building a wall to stabilize the country". He doted on Wanli to the extreme throughout the whole process, and used technology and tactics to protect his family, country and loved ones.
