The whole population collectively enters a flood immersive survival world, and everyone is trapped on a small wooden raft with scarce resources. The protagonist Lin Bei accidentally contracts an ancient Xuanwu turtle, and relies on the turtle's back to build the mobile city-state Xuanwu City. He reclaims farmland, builds workshops, takes in displaced survivors, and sets up fair-priced trading firms without driving up the price of supplies. Facing looting forces such as drifting at sea, Lin Bei relies on city defense to passively resist the enemy, leading the people to stick together, work together, and divide labor to coexist. The series abandons the jungle mentality of the law of the jungle, telling a positive story that only through mutual assistance, joint construction, and adherence to order can human beings survive for a long time.