Thehalvesoftwobodies,onebelongingtoafemaleSwedishpolitician,arediscoveredinthemiddleoftheØresundBridge,whichconnectsCopenhageninDenmarkwithMalmöinSweden.Thebody,cutinhalfatthewaist,hasbeenplacedpreciselyontheborderbetweenthecountries,thusfallingunderthejurisdictionofboththeDanishandSwedishpoliceagencies.Afterfurtherexamination,itturnsoutthatthebodyisthatoftwoseparatecorpses,withonehalfbelongingtoaDanishprostitute.SagaNorén,fromtheSwedishside,andMartinRohde,fromtheDanish,leadtheinvestigationtocatchthemurderer.[4][5aaa
　　Theinvestigationquicklyescalatesasajournalist,DanielFerbé,whosecarwasusedinthecrime,beginsreceivingphonecalls.Thecaller,whobecomesknownasthe"TruthTerrorist",claimstobecommittinghiscrimesinordertodrawattentiontovarioussocialproblems.Asocialworker,StefanLindberg,whosesisterbecomesavictimoftheTruthTerrorist,becomesanearlysuspect.However,eventssoonleadtheDanishandSwedishteamstoconcludethatthekillerhasconnectionstothepolice.Theydiscoverthatthecrimeshavebeenplannedoveraperiodofseveralyears.ThetraileventuallyleadsthemtoJens,aDanishpolicemanandformerclosefriendofMartin's,whowasthoughttohavecommittedsuicideafteranaccidentonthebridgecausedthedeathsofhiswifeandson.
　　Inthecourseoftheinvestigation,MartinandSagadevelopacloseworkingrelationship,althoughtheyareverydifferentpeople.Martinhasatwenty-yearoldsonfromhisfirstmarriage,August,whoisnowlivingwithMartinandhiscurrentwife,Mette,bywhomMartinhasthreechildren;afterMartinhashadavasectomy,Mettediscoversthatsheisexpectingtwins.Sagalivesaloneanddoesnotseemtofeelsheneedsaseriousrelationship,insteadpickingupmeninbarsforcasualsex.SheappearstohavesymptomsconsistentwithAspergersyndrome,resultingindifficultyestablishingrelationshipsandfeelingsofinadequacyinmanagingpeople;sherefusesapromotionforthislatterreason.
　　Afterthekillerhasmurderedseveralpeopleandsuccessfullythrownredherringsinthewayoftheinvestigation,histruepurpose-tostrikeatMartinhimself-eventuallybecomesclear.Jens,nowcallinghimselfSebastianSandstrod,firstapproachesMette,whoissusceptibletohisadvances,afterlearningthatMartinhassleptwithCharlotteSöringer,awomanwhoisperipherallyinvolvedintheinvestigation.SebastianluresMetteandherchildrentoaremotespotwherehesubjectsthemtoaterrifyingordeal,lockingtheminwitharoomandgivingherahandgrenadewithitspinremovedtoholdaslongasshecan.However,SagarealisesthatAugustistherealtarget.Theinvestigationculminatesinaconfrontationonthebridge,whereshecannothelpbuttellMartinwhathappenedtoAugustandhastofireathiminordertopreventhimdestroyinghiscareerbykillingSebastian,thekiller'sfinalintention.