Hundreds of years from now, a meteorite crashes into Earth's surface, gradually raising the planet's oxygen levels and making it impossible for humans to survive aboveground. Humanity is forced to eke out a living underground. After decades of development, the underground population is divided into the Dome District and the Lower District. The Dome District enjoys a prosperous economy and advanced technology, while residents of the Lower District consider even blocks of synthetic protein a luxury.
Cheng Yan is an ordinary man from the Lower District. The moment he happens upon his grandfather's diary, it is as if he has opened Pandora's box and begun exploring the surface world. Before him lie two choices: stay underground, live an ordinary life, and remain an ordinary person, or brave the dangers of the surface and overcome its challenges. Which should he choose? And if he finally returns to the surface, will the world he finds really be what he wanted to see?
