Infernal Affairs [Mou gaan dou]
Directed By: Wai-Keung Lau
A story between a mole in the police department and an undercover cop. Their objectives are the same: to find out who is the mole, and who is the cop.
IMDB Movie Page: http://www.imdb.com/title/tt0338564
The trailer below is provided for reference and connects to a non-BYU site. International Cinema is not responsible for the content.