An unnamed traveller descends into a mysterious chasm and is shocked to find a vast underground society, inhabited by a race of humans he's never seen before. He is taken in by a family, who teach him about their people, who call themselves the Ana, and their utopian society.
The Coming Race contains examples of:
- Applied Phlebotinum: Vril is what the Ana call the power "beyond our mere science" that unifies all forces of nature, which they have learned how to harness. It can do almost anything, from lighting to hypnosis. The vril is so important to them that their word for civilization is "A-Vril," and civilized people call themselves "Vril-ya" to distinguish themselves from the small number of savages who don't use vril. Similar to the quasi-electric fluid in Bulwer-Lytton's Zanoni and A Strange Story.
- Cheerful Funeral: A painless death at an advanced age is seen as a cause for celebration rather than mourning. The narrator attends the funeral of a man who died at the age of 130, where the smiling, happy guests sing an upbeat hymn called "Birth Song" to celebrate the man's Ascension To A Higher Plane Of Existence. After the main service, the narrator's host Aph-Lin hosts an equally joyful banquet at his house.
- Direct Line to the Author: The book presents itself as a nonfiction book about the customs of the Vril-ya that the narrator wrote after the events of the novel.
- Fantastic Racism: Nations that don't use vril are held to be genetically incapable of doing so, and are regarded with "more disdain than the citizens of New York regard the negroes."
- Kids Are Cruel: Killing dangerous animals is considered a job for young children because the younger a child is, the more ruthless they are willing to be.
- Lamarck Was Right: Each Vril-ya has a staff that they use to control vril, and a large nerve in their palm to allow them to easily perform great feats even as young children. Their ancestors developed that nerve over the course of thousands of generations of use and exposure to vril.
- Legend Fades to Myth: The Ana have stories of how their ancestors lived on the earth's surface before fleeing below to escape from massive floods, but most people dismiss them as myths, and don't believe in the existence of a surface at all.
- Mutually Assured Destruction: Vril-based weapons are so powerful that war is pointless, crime is unheard of, and because the government can no longer impose its will on people by force, people live in societies that they move between at will, with governments that attend to practical matters rather than imposing laws.
- Point of No Return: The narrator and an engineer descend into the chasm in a cage, then climb the last fifty feet using ropes and grappling hooks. The narrator climbs down first, but as the engineer follows him, the rock suddenly crumbles, killing the engineer and destroying the narrator's chances of climbing back up.
- Post-Scarcity Economy: Vril powers the machinery that does most of the labor, and what little manual labor is left is done by children, who are paid enough by the government to be independently wealthy by the time they come of age. Because there are no social classes, adults are free to live however they want, with some enjoying what would look to surface-dwellers like absurd luxury, and others preferring a more modest lifestyle.
- They Would Cut You Up: Aph-Lin warns the narrator not to go out alone because the other Vril-ya would quickly realise he wasn't like them, and he would soon attract the attention of the College of Sages, who might dissect him for scientific purposes.
- Xenophobic Herbivore: After thousands of years of eating only plants, the Ana's teeth and digestive systems have adapted so they can't eat meat, and view the idea of eating an animal with horror. When the narrator arrives in their world, he is almost killed because his carnivorous teeth lead the Vril-ya to think that he's a dangerous beast. One reason the protagonist is desperate to return to the surface is that if he stays underground, he might be pressured into marriage and produce a child with carnivorous teeth, and if that happens, he and his child with both be exterminated.
