the gangsters are getting that money from selling drugs or stuff that gangsters do, so the chinese one is their auditor or acountant, he finds out that the police knows about that money and decides to take all of that money away with him, to some place he only knows of, he goes to hong kong since chinese ppl won't turn in someone of their kind to some other country authorities, he goes there to hide and to be safe but both gotham police and gangesters want him, the 1st one cuz he has evidence to get the gangesters to jail and the 2nd ones cuz he has their money.
So batman goes to HK takes him to gotham and police has the evidences they need to get to the gangsters, thats when the action begings

