A violent lab accident leaves drug manufacturer Timmy Choi hospitalised and in the custody of veteran Police Captain Zhang. Facing the death penalty, Choi agrees to turn informant, giving the Police vital information on his partners and their organisation in order to avoid execution. In a bid to take down the powerful drug ring, Captain Zhang and his team are forced to infiltrate Choi’s organisation. But when things spiral out of control, the lines between cop and criminal are blurred as they fight for their survival.