- The Story
- Confidential File
- Making Film
- Dual Ending!
- Infernal Affairs in Korea
- Infernal Affairs in Japan
- Trailers
- Cast & Credits
- Still Gallery
- Easter Egg

The movie is about Yan (Tony Leung Chiu Wai) who is a police undercover
in the Triads while Ming (Andy Lau) is in the reversal of a triad undercover in
the police department. Leading parallel but opposite lives, both feel the
tremendous pressure as well as stressfully trapped in their false and
increasing dangerous surroundings. Both have been walking on the thin fatal
line until on one fateful evening they finally meet each other. On the other
hand, both the police and the Triads have knowledge that there's an
undercover amongst them and the chase is on as they compete who
would 'dig' out their `mole' first.