Tianming Yun, who was suffering from a terminal illness, bought a star and gave it to his college classmate and secret crush, Xin Cheng. However, Cheng Xin, who was involved in the launch of probes toward the Trisolaran fleet as part of the Planetary Interception Array (PIA) project, wanted Cloud Yuntian, who had an aerospace background, to give up euthanasia. As the designated executor, Cloud Yuntian chose to donate his brain to the Staircase Project. The war with the Trisolaran civilization revealed the dark truth of the universe, and Earth's civilization, fearing the strikes from the dark forest, dared not expose itself in space. The warships that initiated the dark battle in the amoral universe were induced to return, only to face judgment by the morally guided Earth civilization.
Incompetent and cowardly Xin Cheng was chosen to be the Swordholder, someone who held the fate of Earth in her hands. She saw this as a task that only required time, inspired by Ji Luo's success. However, as soon as she took office, the Droplet launched an attack on Earth. Xin Cheng made a wrong decision in order to remain loyal to human nature. The Blue Space, which continued to fly under the warning, was pursued by the Universal Gravity, a ship capable of launching gravitational waves, as well as two accompanying Droplets. The personnel on board entered four-dimensional space, destroyed the Droplets, captured the Universal Gravity, and initiated a gravitational wave broadcast, revealing the coordinates of the Trisolaran system to the universe.
Tianming Yun made contact with Earth and revealed a significant amount of information to Cheng Xin through three fairy tales he had created. Humanity believed they had discovered the secret to survival and began implementing the Shelter Plan. However, due to Cheng Xin's erroneous judgment, the space curvature drive research led by Wei De was terminated, ultimately preventing humanity from escaping the fate of destruction by advanced civilizations. Because there were even more powerful civilizations in the universe, the methods and weapons of war exceeded human imagination. A highly advanced civilization released a "two-dimensional foil," the size of a card, compressing the entire solar system into a two-dimensional plane and destroying it.
As Earth's human population neared extinction, only Xin Cheng and AA were able to escape on a spaceship traveling at the speed of light. Ji Luo became the "Gravekeeper" at the Earth Civilization Museum set on Pluto, while Xin Cheng and AA took the essence of human civilization with them on Pluto. On a planet of the star gifted by Tianming Yun, Xin Cheng encountered Yifan Guan and explored the truth of cosmic dimension reduction. However, a force beyond all others demanded the universe to reset to zero and be reborn. Xin Cheng traversed the vast expanse of time, lasting 18 million years, in the dark domain... Without waiting for Tianming Yun's arrival, she resided briefly with Yifan Guan in the small universe before re-entering the vast universe for a new life.
