無間道
Infernal Affairs is a 2002 Hong Kong action thriller film co-directed by Andrew Lau and Alan Mak. Jointly written by Mak and Felix Chong, it stars Andy Lau, Tony Leung, Anthony Wong, Eric Tsang, Sammi Cheng and Kelly Chen. The film follows a police officer who infiltrates a Triad, and another officer secretly working for the same gang. It is the first in the "Infernal Affairs" series and is followed by "Infernal Affairs II" and "Infernal Affairs III".