Simple genre filler, that lacks the edge (pun) usually present in Herman Yau's oeuvre. It's a very straightforward Triad crime flick, with some very familiar names taking on roles they've played countless times before. It's certainly good enough if you're craving a bit of Hong Kong Triad action, but that's about all you can expect from it.
Harry Sin has been an undercover cop for 8 years straight. When his operation finally comes to an end, the major bosses of the Triad gang he infiltrated are apprehended and Harry can go back to his normal life. After so much time living and working in the criminal underworld, the switch is quite a bit harder than Harry imagined.
The 00s were a transitional decade for Yau. He transformed from a dedicated, edgy B-film director to someone who could also do bigger, more commercial genre projects. Like most Hong Kong directors, Yau learned the tricks of the trade on the job, and so he made quite a few decent but unremarkable genre films to get the hang of them. On the Edge is one of those films. Solid, but forgettable filler.