When the apocalypse breaks out, Lin Shuangshuang, who possesses extraordinary combat abilities, develops short-term memory impairment, and her memory keeps shrinking until she can remember things for only seven seconds. She relies entirely on the notes on her wristband to maintain her sense of identity. She reunites with her former lover, Huo Ling, and joins his mobile fortress squad. The team struggles to survive in the post-apocalyptic world, fighting infected people, mutated beasts, and evil human factions. Lin Shuangshuang harbors a secret: her body was modified in the XD0 experiment, and her contamination level constantly threatens her sanity. After enduring acid rain, extreme cold, zombie hordes, isolated-island missions, and countless other crises, she battles her fading memory while uncovering her own past. She also encounters the former squad she belonged to before losing her memory. In the end, she chooses to stay with the companions she has now.