The film revolves an undercover police officer who attempts to take down a drug trafficking syndicate from the inside.

The chief investigator of Hong Kong’s Independent Commission Against Corruption (ICAC) is banking on a key witness, the corporate accountant Jack (Nick Cheung Ka-fai), to testify in court against a high-level customs officer and a tobacco trading company CEO accused of bribery and smuggling. When neither Jack nor the CEO show up on the day of the hearing, King is given seven days to save the prosecution’s case.