Sixteen-year-old Xie Linchuan comes from Shihe Village on Qingheng Mountain to Jiangzhou. He only wants to attend classes, take exams, go to the mall, and learn how to use a smartphone like an ordinary high school student. But his grandfather trained him from childhood to develop an almost instinctive ability called the “return line”: when danger appears, his body automatically finds the quickest way to incapacitate his opponent. In the age of underground cities, this lethal skill, which should have stayed hidden in the mountains, is caught on livestream again and again. A breach at the South Station, a school accident, an unauthorized expedition: the more he tries to stay out of the spotlight, the more the entire internet pushes him into it. Worse still, an old case involving seven deaths on Qingheng Mountain two years ago is leaked. The “hero who saved lives” suddenly becomes a teenage murderer in the eyes of the internet, while an old organization called the Gray Gate begins pursuing him and the secrets his grandfather left behind. Xie Linchuan must learn more than how to defeat monsters. With everyone watching, he must decide what kind of person he wants to become.
