In ICAC investigations into the corrupt activities, senior investigators lead newly-joined assistant investigators to work relentlessly to maintain a fair and just society, facing huge challenges…

Electoral fraud
While visiting her grandmother in a public housing estate, ICAC senior investigator Au Man-Wing (Natalie Tong) happens to learn that Ng Tak-Cho (Lawrence Cheng), a candidate of District Council by-election, exploited loopholes to provide cheaper meal and free flu shots to residents there as an inducement to vote for him. So she promptly reports it to chief investigator Pao Siu-Chung (Chris Lai) and launches a probe..