The narrative begins sometime around the 1930s with the discovery by young journalist Howard Homfrey of survivors and descendants of a ship which ran aground in the Pacific in 1902. The first section of the novel then provides insight into the utopian society which has evolved, and which has also developed a number of technological marvels - including a form of television, electric roadways and 'private flyers' or aerials. Mail is also delivered by pneumatic tubes.
One of the Lava Islanders, Alan Edgecumbe, eventually accompanies Homfrey to Auckland, New Zealand, and later Sydney, where he later attracts the romantic attentions of Hortense Pelham, "a femme formidable and scientific genius' (Stone, p. 116), and who invents the most powerful explosive in existence.
During the course of the story a war between the Chinese and Americans breaks out, with Australia caught in the middle and attacked by Chinese forces which have access to formidable weapons (including laser-like heat rays). When Pelham finally realises that Edgecumbe is not interested in her she obliterates her mansion in an attempt to make people believe she is dead. While travelling through Arabia some time later Edgecumbe discovers that not only is she alive but has become the sorceress queen of a warlike tribe of Arabs. His presence and discovery eventually proves too much for Pelham and she "incinerates herself by a patent process of her own invention (p. 78)."