Manufacturing just fifty grams of meth in China will earn you a death sentence. Timmy Choi (Louis Koo) has manufactured tons, and after a violent lab accident, he's in the custody of Captain Zhang (Sun Honglei). Now, he has only one chance to avoid execution: turn informant and help Zhang's undercover team take down the powerful cartel he's been cooking for. But as the uneasy allies rush to execute a months-long operation in just a few days, the increasingly desperate police are quickly stretched past their limits. As things spin wildly out of control, the line between duty and recklessness is blurred, and it becomes unclear whether Zhang or Choi actually has the upper hand. Long considered the master of the Hong Kong crime thriller, Johnnie To's first mainland production eschews "two guns at once" mayhem in favor of atmosphere and a tightly-wound plot punctuated with impeccably choreographed bursts of startlingly realistic violence, in this intricate puzzle box of a film that ignited a firestorm of controversy in its homeland upon its release.