It's remarkable and quite praiseworthy how writers and directors continue to make great movies out of one of the oldest and most (over)used story lines in cinema! "Dog Bite Dog" is basically not much more than just the simple story of an lone copper obsessively chasing a brilliant criminal, only Pou-Soi Cheang distinguishes his film from the rest by being extremely violent & relentless. This is unquestionably one of the grittiest and most uncompromising movies I've ever seen, with an atmosphere of constant nihilism and characters that seem to come walking straight out of hell! Not even the installments in Chan-Wook Park's trilogy of vengeance (with the exception of "Oldboy", perhaps) or any other infamous Cat-III film ever released were as sadistic and brutal as some of the events depicted in "Dog Bite Dog". Pang is a young and ruthless Cambodian assassin who lands in the crowded streets of Hong Kong to eliminate the wife of an eminent judge in a restaurant. When the police arrives at the place, young officer Wai sees how Pang hastily flees from the scene of the crime and follow him. The first actual confrontation between the two rabid dogs results in a gigantic blood bath, as Pang mercilessly kills several hostages and even Wai's long time friend and colleague. From then on begins a thrilling and action-packed cat and mouse game between the frustrated cop and the professional killer. The latter also saves a young girl from the constant sexual abuse of her father and stays with her at her shed in the local garbage dump. What makes this routine action/thriller so fascinating (apart from the explicit violence) are the main characters' backgrounds! Pang, the hit-man, is a Cambodian orphan and has been trained to fight & kill for money ever since he was a child. He knows no restrictions, has no mercy and barely speaks a word. Wai, the cop, became particularly ruthless and unorthodox ever since his role-model father (also a cop) lies in a coma after a drug-related incident. Lai doesn't question suspects and witnesses; he yells at them and he's prepared to sacrifice everything in order to stop his brand new nemesis. People with a weak stomach or tangled nerves are advised to stay away from this film, because the cruelty and shocks featuring in "Dog Bite Dog" can easily cause nausea. It's not the type of violence where bloodied heads and chopped off limbs fly through the air, but more like the intense and utterly disturbing type where people attempt to crush their opponents mentally as well as physically. The filming locations are effectively dark and eerie and the extremely sober music makes the already harrowing tone of the movie even more petrifying. The performances are terrific! I wouldn't be surprised if Edison Chen and Sam Lee treated each other like enemies on the film set as well, because their on screen hatred and disgust feels a little too legitimate. "Dog Bite Dog" is a powerful and unforgettable film, highly recommended if you can stomach it. If you fear you can't, just wait a few years for the inevitable American remake which will unquestionably soften the premise a little.