Extending the topic of undercover cops after the point where other movies may have left off, Herman Yau's accomplished On The Edge follows a young officer struggling in his return to the regular uniformed force. For Harry Sin (Nick Cheung), coming off his long stint as a mole is no easy task. Sin had been sent to infiltrate a gang led by don Dark (Francis Ng) and, once his target is nabbed, he's handed a bravery certificate and a paltry bonus, rehoused, then put straight onto the beat. But four years is a long time undercover, especially for an agent plucked straight from the training academy: Where do his allegiances stand? His nightclub hostess girlfriend of two years, Cat (Rain Li), isn't in a rush to rekindle the flames of their relationship. And it doesn't help that his first partner back on the force is Lung (Anthony Wong) -- an officer not known for a gentle hand with gangsters -- and that internal affairs' investigators are duty bound to treat him with suspicion.
On The Edge marks a return to more politically charged filmmaking for Herman Yau, but the director changes tack here. Unlike the ambitious campaigning of From The Queen To The Chief Executive or the fun blend of social issues and comedy in Shark Busters, Yau's latest is more concerned with driving home the harsh life of the ex-undercover cop, and the identity crisis that comes with the dramatic change. As a character study, On The Edge is fascinating stuff. Building into an intriguing supplement to other movies on the topic including the Infernal Affairs trilogy, and nimbly crosscutting between the two phases of Sin's career onscreen, the picture Yau paints is far from pretty. The young cop seems even more helpless for having no family to turn to, and everything is set up to offer few surprises. Yet the filmmakers are careful to add measures of light to the tale, whether developing gang boss Dark into a likable rogue or throwing in a highlight smash-'em-up with police vehicles.
Playing the complex Harry Sin part, actor Nick Cheung adds another commendable dramatic role to his filmography after his recent runs in Johnnie To's Election series. Anthony Wong is another quality draw as his rough partner while Francis Ng takes on an offbeat, relaxed gangster role with characteristic style. Rounding out the leads, Rain Li is fine as the gangland girl unlucky enough to fall for a mole and Derek Tsang ably takes on the part of Sin's troubled friend. The high standard of the lead actors lifts the production, offsetting On The Edge's otherwise overcast and sometimes low-budget appearance, and extending the appeal of Yau's small-scale yet focused and ambitious drama.