A year before Infernal Affairs rejuvenated Hong Kong cinema, Eric Tsang was already playing an affable yet brutal mob boss in an ‘undercover cop drama’, COP ON A MISSION, which didn’t get much attention but deserved its fair share of it. It tells of Mike (Daniel Wu), a driven cop who is assigned to an undercover mission in triad boss Yum’s (Eric Tsang) circle. But he is soon seduced not only by the glitzy world he has infiltrated, but also by Yum’s beautiful wife Pauline (Suki Kwan). As he grows more and more estranged from his real life, including his kind girlfriend (Anya), and is given more and more power by the trusting Yum, Mike’s moral compass threatens to go awol.
It’s not difficult to see why such a film would get overshadowed and somewhat forgotten in the wake of the Infernal Affairs trilogy’s enormous success. COP ON A MISSION has an altogether much less polished package, though it is directed with maximum efficiency by hard-working editor Marco Mak (who edited virtually every Hong Kong classic of the nineties) ; the cast is less glamorous (Wu and Tsang being the only big names), and the script is less tortuous. But contrary to many of its kind, Marco Mak’s film doesn’t desperately try to be mind-blowing, it shoots for “fun and engrossing” and hits its target.
The “fun” part are the b-movie stylings, with rapid-fire shootouts (though not many) expertly choreographed by Ma Yuk-Sing and Daniel Wu’s growingly unhinged performance. Wu was only starting out at the time, and wasn’t yet the accomplished actor he is becoming these days. His performance is a simple and enjoyable one, transitioning from the puppy eyes and agape mouth of the undercover cop getting to grips with the triad world and falling in love with his boss’ wife in the beginning, to a collection of smirks and slightly wild eyes as his character’s soul starts to rot.
As for the “engrossing” flipside, it is carried out through a tight script that ably toys with the frontier between right and wrong, locating it in unexpected places, as the audience discovers that underneath boss Yum’s creepy eyebrows and sometimes startlingly brutal ways (he kills one of his men in the middle of a friendly dinner, much like Al Capone in The Untouchables) is a loving man who despite being on the wrong side of the law has a deceptively moral core. Eric Tsang is of course terrific, using his rotund features and hollow voice expertly, in what is indeed a convincing test run for his better-known role as Hon Sam in Infernal Affairs. And COP ON A MISSION, familiar though it may seem, does manage to sneak in a few suprises for the audience, including an oddly satisfying ending that is a welcome change from the usually bitter codas this kind of undercover cop thriller usually dishes out.
Long Story Short : A familiar and almost second-rate undercover cop thriller on the surface, COP ON A MISSION is nevertheless enjoyable and tight, featuring a great Eric Tsang performance and managing to introduce a few interesting twists to the formula. 
1/2
