Special ID (2013) on Netflix

Plot summary

A failed negotiation with three other local gangs leaves Cheung Mo-Hung doubting Chan Chi-Lung, who has spent years inside the triad as a police infiltrator. Hung moves to clear every undercover officer from his ranks, and Lung, sensing the danger, asks his captain to end the assignment. He is sent instead into Mainland China to break the Special Identity trading business run by Sunny, once his closest friend in the gang and now Hung's protégé. The captain promises Lung his police identity back once Sunny's operation falls. Mainland officer Fang Jing and her chief Lei Peng work alongside him. Lung is also trying to hold his family together while keeping the job hidden.