In Hong Kong, the lead investigator for the Independent Commission Against Corruption (ICAC) is relying on a crucial witness, corporate accountant Jack (played by Nick Cheung Ka-fai), to provide testimony in court against a senior customs official and the CEO of a tobacco trading firm, both charged with bribery and smuggling. However, when both Jack and the CEO fail to appear on the day of the trial, King is left with just seven days to salvage the prosecution’s case.