The Coming Race drew heavily on his interest in the occult and contributed to the birth of the science fiction genre. Unquestionably, its story of a subterranean race of men waiting to reclaim the surface is one of the first science fiction novels. The novel centres on a young, independently wealthy traveler (the narrator), who accidentally finds his way into a subterranean world occupied by beings who seem to resemble angels, who call themselves Vril-ya. The hero soon discovers that they are descendants of an antediluvian civilisation who live in networks of subterranean caverns linked by tunnels. The narrator suggests that in time, the Vril-ya will run out of habitable spaces underground and will start claiming the surface of the earth, destroying mankind in the process, if necessary. (Summary compiled from Wikipedia)