It's Not Too Late to Back up Mountains and Rivers

The air quality of Ninth Library is up to standard Xu Li has been repairing fans for eleven years. The first time he had a question was because the children in the nursery always had headaches after taking naps. The instrument did not alarm, maintenance orders were not accepted, and the air duct in the file that had been deactivated was still delivering fresh air at night. Someone is breathing for a district that doesn't exist on the population charts. In order to take a breath, he turned to a project directory before 1991. People at that time still lived on the ground and would look up at the moon after working overtime. They said these places were just temporary accommodation. Later, "temporary residence" became a lifetime for several generations. Thirteen mountain and river reservoirs have preserved seeds, crafts, knowledge and the lives of generations of Chinese people. Underground workers have saved many people; now the surface is not inaccessible, but underground equipment is getting older. Ventilation, water extraction, heat removal and production connect the underground to the surface. In 2126, Xu Li, the leader of the ventilation team, just wanted to keep the home his mother was familiar with and the job of the team. However, due to an anomaly in a nursery, he began to pursue: Whose life is this city saving?