AmericanpsychologistJohnHoldenarrivesinLondontoparticipateinasymposiumaimingtoexposewitchcraftanddevil-worshipasafraud,withattentioncenteredonacultrunbyaJulianKarswell.Debarkinghisplane,Holdenlearnsthatthesymposiumleader,HenryHarrington,hassuddenlydiedandheisnowincharge.WhatonlytheaudienceknowsisthatHarringtonwasclearlykilledbyademon,apparentlysummonedbyKarswelltoavengehispersecution.DespiteboththreateningandcajolingbehaviorbyKarswell,Holdendeterminestoproceed,thoughtheonlycultmemberwillingtotalkabouthisexperiencesisinaprisonpsychiatricward,catatonicafterallegedlykillingyetanothercultmember.However,Harringtonsbelongings,aparchmentidenticaltooneHarringtonrecordedhavinghadpassedtohiminasimilarmannershortlybeforehisdeath...[N.B.HoldenatnopointstaysattheKarswellestate].
