Xu Ning, who was left destitute by a former friend, discovers a bronze door in his ancestral home that can transport him to another world. This discovery opens up a path to wealth as a cross-world merchant. He trades modern items like bottles for ginseng, mirrors for caterpillar fungus, and medicines for gold. In the modern world, he becomes the world's richest man, while in the other world, he wields advanced weapons. With machine guns, mortars, and Gatling guns, his modern arsenal is unmatched. No matter the martial arts, siege engines, or crossbows, he has the upper hand. In the face of emperors and grandmasters, Xu Ning stands as the true ruler of the other world.