This novel centers 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 and call themselves Vril-ya. The hero soon discovers that the Vril-ya are descendants of an antediluvian civilization who live in networks of subterranean caverns linked by tunnels. It is a technologically supported Utopia, chief among their tools being the "all-permeating fluid" called "Vril," a latent source of energy which his spiritually elevated hosts are able to master through training of their will, to a degree which depends upon their hereditary constitution, giving them access to an extraordinary force that can be controlled at will. The powers of the will include the ability to heal, change, and destroy beings and things; the destructive powers in particular are awesomely powerful, allowing a few young Vril-ya children to wipe out entire cities if necessary. It is also suggested that the Vril-ya are fully telepathic. The narrator states that in time, the Vril-ya will run out of habitable spaces underground and start claiming the surface of the Earth, destroying mankind in the process if necessary. Vril in the novel The uses of Vril in the novel amongst the Vril-ya vary from an agent of destruction to a healing substance. According to Zee, the daughter of the narrator's host, Vril can be changed into the mightiest agency over all types of matter, both animate and inanimate. It can destroy like lightning or replenish life, heal, or cure. It is used to rend ways through solid matter. Its light is said to be steadier, softer and healthier than that from any flammable material. It can also be used as a power source for animating mechanisms. Vril can be harnessed by use of the Vril staff or mental concentration. A Vril staff is an object in the shape of a wand or a staff which is used as a channel for Vril. The narrator describes it as hollow with 'stops', 'keys', or 'springs' in which Vril can be altered, modified or directed to either destroy or heal. The staff is about the size of a walking stick but can be lengthened or shortened according to the user's preferences. The appearance and function of the Vril staff differs according to gender, age, etc. Some staves are more potent for destruction, others for healing. The staves of children are said to be much simpler than those of sages; in those of wives and mothers the destructive part is removed while the healing aspects are emphasized. The destructive force is so great that the fire lodged in the hollow of a rod directed by the hand of a child could cleave the strongest fortress or cleave its burning way from the van to the rear of an embattled host. It is also said that if army met army and both had command of the Vril-force, both sides would be annihilated. Interestingly, the Vril-ya also use Vril to take baths: It is their custom also, at stated but rare periods, perhaps four times a-year when in health, to use a bath charged with Vril. They consider that this fluid, sparingly used, is a great sustainer of life; but used in excess, when in the normal state of health, rather tends to reaction and exhausted vitality. For nearly all their diseases, however, they resort to it as the chief assistant to nature in throwing off the complaint.