Hisfirstthreevictimsendedupdead.Hisfourthwasnotsofortunate…AlisonWillettsisunluckytobealive.Shehassurvivedastroke,deliberatelyinducedbyaskilfulmanipulationofpressurepointsontheheadandneck.Shecansee,hearandfeelandisawareofeverythinggoingonaroundher,butiscompletelyunabletomoveorcommunicate.HerconditioniscalledLocked-InSyndrome.InleavingAlisonWillettsalive,thepolicebelievethekillermadehisfirstmistake.ThenD.I.TomThornediscoversthehorrifyingtruth;itisn'tAlisonwhoisthemistake,it'sthethreewomenalreadydead."Anappropriatemarginoferror"ishowtheirkillerdismissesthem,andThorneknowstheyareunlikelytobethelast.Forthekillerissmart,andhe'sgettinghiskicksoutoftoyingwithThorneasmuchasheispursuinghissickfantasy.Thorneknowsimmediatelyhe'snotgoingtocatchthekillerwithsimpleprocedure.Butwithlittlemorethangutinstinctandcircumstantialevidencetodamnhischiefsuspect,anesthetistJeremyBishop,hispursuitofhimissoonborderingontheunprofessional.EspeciallyconsideringhisinvolvementwithAnneCoburn,Alison'sdoctorandJeremy'sclosefriend.Thornemustfindamanwhoseagendaisterrifyinglyunique,andAlison,theonepersonwhoholdsthekeytothekiller'sidentity,isunabletospeak…