Sergeant VoighttriestofindoutwhoisbehindthemurderofJin,andcomeupwiththeunbelievablediscoveryandlearnedthatSergeantEdwinStillwellplayingadoublegamewiththeintentionofgettingoutonthesurfaceofthebigfishalongwithVoight.In themeantime,allmembersoftheintelligencedepartmentsreceivedeaththreatsfromanunknowngroupcalled"Shadow".AtseveralplacesinChicagoinafire,explosion,androbbery,forwhich"Shadow"takesresponsibility,bringingthecityintochaos.