In the apocalyptic city "Gear City" filled with brass pipes and filled with steam, a strange disease called "rust disease" is spreading. Starting from the joints, the patient's body will gradually be replaced by cold metal gears, and eventually become an out-of-control mechanical puppet. The heroine Wen Lai is a skilled cultural relic restorer who specializes in restoring precision machinery from the previous era. While repairing the remains of an out-of-control "rust disease" patient (officially called a "scrap"), she accidentally discovered a tiny gear that did not belong to any known model in its core clockwork. This abnormal gear became the only key to uncovering the huge conspiracy in the entire city. As the investigation deepens, she forms an alliance with Jing Chi, an underground boxer who is running to save her sister, and discovers that "rust disease" is not a disease, but a man-made "forced evolution" experiment targeting the entire city's residents. The highlight is that the heroine did not use any superpowers or combat skills throughout the whole process. She only relied on her professional knowledge as a cultural relic restorer - her ultimate insight into mechanical structures, her precise judgment of metal fatigue, and her patience and meticulousness in repairing antiques - to solve the puzzle step by step, and finally save the entire city from a mechanical empire behind the scenes.
