In Jiangcheng, where neon and steel intersect, loan shark collector Chen Yan uses his fists to collect debts and a machete to keep accounts every day. When he was forced to collect a century-old "Kowloon debt" for his mysterious employer, he discovered that the city was home to nine martial arts families - the Lei family who used high-voltage electricity to practice boxing, the Luo family who set up sword arrays in subway tunnels, and the Su family who relied on VR illusions to cultivate their minds. The debtor is the only conservative among the nine families who refuses modernization: the ancient clan that uses abacus to nuclear explosion internal power and uses account books to write martial arts secrets.
