Twelve years after the devastating eruption of the Krakatoa volcano in the strait between Java and Sumatra, the country still cannot find peace. A yellow mist rises from the depths of the earth, and terrible creatures appear from there at night. Strange horned creatures terrorize the local population. The Governor-General of the Dutch East India Company is concerned about the increasing number of attacks. He turns to his minister of foreign affairs, who, in turn, asks for help from the director of the University of Berlin.