?Followingonemulti-strandedinvestigationoverfivehours,LineOfDutyseesDetectiveSergeantSteveArnott(MartinCompston)transferredtoAC-12,afictionalanti-corruptionunit,afteramistakenshootingduringacounter-terroristoperation.AlongsideDetectiveConstableKateFleming(VickyMcClure),theyareassignedtoleadaninvestigationintotheallegedcorruptionbyapopularandsuccessfulofficer,DetectiveChiefInspectorTonyGates(LennieJames).WhileGatescleverlymanipulateshisunit’sfigures,DSArnottquestionswhetherGates’sbeingmadeascapegoatforacultureofinstitutionalisedspin,orisguiltyofdarkercorruption?