根據真實案件改編。青年馬家杰被控告通過郵寄販運毒品，在辯護律師建議下承認控罪換取減刑。然而，從警察轉職檢控官的霍子豪發現案件非比尋常，毅然暗中展開調查。簡單案件背後牽涉複雜犯罪集團？檢控販運毒品又是否存在誤判？
Based on true events. A young man is charged with drug trafficking. He pleads guilty under undue influence from his defense lawyer, in exchange for a reduced sentence. Hard-edged former cop Fok (Donnie Yen) is the unconventional prosecutor assigned to the case. He becomes convinced that the conviction is unusual and decides to conduct his own investigation. Fok is forced to risk his own life and career to uncover the truth and bring the real villains to justice.