Xu San San, a twenty-year-old medical university student and emergency department intern, awakens in a pitch-black warehouse with a severe wound on her left arm. She realizes she has transmigrated into the body of a fifteen-year-old girl with the same name, who died after falling from ruins in a post-apocalyptic world. Clutching an emergency medical kit she grabbed before losing consciousness, Xu San San uses her medical knowledge to treat her own injuries, administering a tetanus shot and cleaning the wound. She discovers a high-tech wristband, which she identifies as an Optical Brain, displaying her identity as a Scavenger in Refugee Camp 9-004, located outside Base City 103. Her lease on a room in the Outer City is expiring, and she possesses only thirty-eight Contribution Points, far short of the four hundred needed for renewal.
The next morning, Xu San San is mistaken for a reanimated corpse when she wakes up in the barracks, which is filled with hundreds of motionless, emaciated refugees. A middle-aged worker scanning bodies for cremation panics and alerts the Guard Team. Captain Wang arrives and confirms through her Optical Brain that she is alive, though barely. He warns her that the Ninth District is dangerous for the living and urges her to leave. Xu San San escapes and discovers that the person lying beside her the night before is actually alive. This young man is Xie Yuan, an Advanced Gene Warrior and captain of the Dawn Guard, who had been ambushed and poisoned during a mission in Wasteland City 505. He had hidden his identity by wrapping himself in rags and pretending to be a corpse to avoid detection by the traitor who betrayed him.
Xu San San performs emergency surgery on Xie Yuan, removing a bullet from his abdomen without anesthesia. She then drags him on a flatbed cart to the Eighth District, which appears less hostile, before returning to her rental unit in Zone Z to pack. She learns that the city gates close at 6:00 PM, barring non-residents from staying outside. Forced to return to the Refugee Camp, she encounters a black-market seller of Nutrient Solution. Using her wits, she negotiates a low price for expiring stock, securing food for herself and the injured Xie Yuan. That evening, scavenging teams return to the camp, revealing the harsh cycle of survival in this world. Xie Yuan, unable to move, communicates by writing on Xu San San's palm. He provides her with coordinates to a vacant plot in the Shantytown, based on information he overheard, offering them a chance to establish a secure shelter.
Xu San San pulls the cart through the dark to the coordinates, setting up a makeshift tent in the Shantytown. She cares for Xie Yuan, feeding him nutrient solution and water, and tends to his wounds. The wristband announces upcoming scavenging missions to the Wilderness and Wasteland City 107. Xu San San decides to participate in the missions to earn Contribution Points and secure their survival. As she prepares for the first mission, she navigates the complex social hierarchy of the Base, the dangers of the wasteland, and the hidden agenda of the traitor within the Dawn Guard who targeted Xie Yuan. The story follows her adaptation to this brutal new world, leveraging her medical expertise and modern knowledge to protect herself and her injured companion while uncovering the mysteries of the apocalypse.
