Long considered the master of the Hong Kong crime thriller, Johnnie To's first mainland production turns an eye on China's rising, ultra-violent drug epidemic. In China, manufacturing just fifty grams of meth will get you the death penalty. Timmy Choi has manufactured truckloads of it, and after a violent lab accident he's in the custody of Captain Zhang. 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 are forced to compress months of police work into 72 sleepless hours, things begin 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.