I am invisible. I am inaudible. The enemy's fate is in my hands.

The head of an elite Hong Kong surveillance unit keeps one eye on his rookie apprentice and the other on a notorious criminal he suspects of masterminding a recent jewel heist in this tense thriller from filmmaking duo Johnnie To and Nai-Hoi Yau. Of course, the criminal knows all along he's being watched. But that doesn't stop him from trying to pull off the biggest score of his career.