Thestakesareraisedinseasontwoof"MI-5",asthethreattonationalsecurityincreasesandtheneedtothwarttheterroristsoperatingwithintheUKbecomesmoreurgent.TomisinvestigatingaSerbianterroristplot.HisgirlfriendandherdaughteraretrappedinTom'shousewithalap-topwhichisthoughttocontainabomb.MeanwhileanotherbombisprimedtoexplodeandthisonekillstheSecretaryofStateforNorthernIreland.Addingtothepossibledangersfacedbyothergovernmentofficials,TomlearnsfromhisAmericancolleaguethatanassassinisintown,theCIAknowabouthimbuttheyhaven'ttoldMI-5.