Battler Ushiromiya returns after six years to his family's annual gathering on the private island of Rokkenjima, where his relatives quarrel over the inheritance of the ailing patriarch Kinzo. Kinzo clings to life dreaming of the golden witch Beatrice, said to have given him his fortune long ago. A typhoon then seals the eighteen family members and servants on the island, and a letter signed by Beatrice arrives. People begin to vanish in a chain of impossible murders, and the survivors argue whether a human killer or the witch herself is at work.