The world has become a dystopian nightmare, with a deadly black fog enveloping all lands below 3000 meters. The only refuge for humanity is found in Baita City, perched atop a mountain. Mu Cheng and his sister cling desperately to each other in this harsh world, but when Mu Cheng's hidden powers suddenly awaken, he is consumed by anxiety. One day, a mysterious group takes hold of Mu Cheng and thrusts him out into the dangerous fog. To his surprise, he stumbles upon thriving communities and other secrets hidden beneath the mountain's surface.
