Infernal Affairs(2016)

Infernal Affairs is a crime series that follows mainland CID officer Jiang Zidan, codenamed "Bullet," as he infiltrates a Hong Kong triad to investigate cross-border drug trafficking. His swift intelligence earns him favor with triad leader Wu Koon-yau, but Bullet doesn't know that narcotics inspector Wai Chun-hin is the trusted mole of the triad's ambitious deputy leader Hon Long. When Wu's daughter is kidnapped, long-buried tensions between the two triad factions explode into open conflict. Chun-hin's unauthorized rescue attempt costs him his badge, though he continues working undercover with fellow officer So Ching. As Hon Long schemes to consolidate power through any means necessary, the lines between cop and criminal blur. Bullet, Chun-hin, and Hon Long become locked in a dangerous game of deception where trust is a weapon and survival depends on staying one step ahead.