After narrowly escaping Wei Zhuang's assassins, Jing Tianming, Ge Nie, and their allies seek refuge in Mechanical City, the Mohist School's impregnable stronghold hidden deep in the mountains. Protected by hundreds of traps and mechanical beasts, the fortress remains one of the few places untouched by the Qin Empire and is a haven for those conspiring to overthrow the empire.

Unfazed by the challenge of breaching such a secure fortress, Wei Zhuang enlists the help of the infamous Gongshu clan, who are known for their aggressive, war-focused mechanical technology. Armed with their deadly inventions, Wei Zhuang sends a specialized force to infiltrate Mechanical City, aiming to sow turmoil within their ranks and bring them down from within.