《芝加哥警署第二季》讲述的是：SergeantVoighttriestofindoutwhoisbehindthemurderofJin,andcomeupwiththeunbelievablediscoveryandlearnedthatSergeantEdwinStillwellplayingadoublegamewiththeintentionofgettingoutonthesurfaceofthebigfishalongwithVoight.Inthemeantime,allmembersoftheintelligencedepartmentsreceivedeaththreatsfromanunknowngroupcalled"Shadow".AtseveralplacesinChicagoinafire,explosion,androbbery,forwhich"Shadow"takeresponsibility,bringingthecityintochaos.