AmericanpsychologistJohnHoldenarrivesinLondontoparticipateinasymposiumaimingtoexposewitchcraftanddevil-worshipasafraud, withattentioncenteredonacultrunbyaJulianKarswell.Debarkinghisplane, Holdenlearnsthatthesymposiumleader, HenryHarrington, hassuddenlydiedandheisnowincharge.Whatonlytheaudienceknowsi...