The narrator "Smith" tells his story in the first person. A traveler and amateur naturalist, he regains consciousness "under a heap of earth and stones" and believes that he had been knocked unconscious in a fall  though his thoughts and recollections are confused. He is astounded to discover that he is entwined in the roots of plants, as though they have been growing around him. Extricating himself and surveying the scene, he sees a great house in the distance, and walks toward it to seek help and information. On his way, he encounters a funeral: a group of strangely yet strikingly dressed people, led by a majestic white-bearded old man, are interring a corpse in a grave. The narrator is especially struck by a beautiful girl who is overcome by grief. She appears to be about 14 years old; though, he soon learns that this world, and everyone in it are far older than they appear. He becomes enchanted by her, and falls in love. The funeral party see him, and express surprise at his presence and his odd uncouth clothes and boots; but they allow him to accompany them to the enormous mansion where they live.
Enthralled with the girl (her name is Yoletta), and anxious to show his worth in their House, the narrator agrees to work for a year as a probationer in this community. He is constantly stumbling into misunderstandings with his new companions, for the world seems to have changed in so many extreme and incomprehensible ways. The most basic concepts of his society are unknown to these people. When he inquires about the nearest city, the old man who is "the Father of the House" thinks he is talking about a beehive. When the narrator notes that they share the English language, he is again not understood; the people of the house think they speak "the language of human beings  that is all." (Though their spoken language has changed little, the writing system is altered so much that the narrator cannot read the "Hebrew-like characters" in which their books are written.) It seems that the entire human race is now organized into communal houses like this one, with no other form of social structure, that they know of.
The narrator struggles to adapt to this new society, as he pursues Yoletta. He is shocked to learn that all the people are much older than they appear; Yoletta is 31 years old, and the Father of the House is nearly 200. They are vegetarians, and have a strong rapport with the animals in their environment. The narrator is struck by their "rare physical beauty," their "crystal purity of heart," "ever contented and calmly glad". Yet he wonders why they have no romantic interests, and why there are no children in the community. He sometimes falls afoul of the strict rules, in which lying is a serious offense, punishable by solitary confinement. Yoletta comes to love him, but like a brother, without the heat of passion he feels for her.
In time he meets the mysterious Mother of the House, and begins to comprehend the full strangeness and differentness of their way of life. The humans of this distant future have achieved their utopian state by abandoning sexuality and romantic love. Like a beehive, or a wolf pack, only the Queen, or Alpha Male and Female, or Father and Mother of the House, in this case, reproduce. The rest of the House live communally, as siblings. The narrator despairs when he realizes that his passion for Yoletta can never be consummated; and, wonders whether he can adapt to this mode of living. He does not realize that the Mother has begun the long process of grooming himself and Yoletta to become the new Father and Mother of the House.
When he is in the library, he discovers an elaborately-carved bottle on a shelf; its inscription states that its contents provide a cure for the oppressions of "time and disease" and the thoughts or passions that "lead to madness." He takes a dose of the liquid, thinking it will cure his passion for Yoletta, which he doesn't realize she has begun to learn to reciprocate. It is only when his body grows stiff and cold that he realizes that the potion is a poison, and that the only relief from the pains of life it provides is death.
This story, of a traveler who falls in love with a mysterious, beautiful young girl with an elderly protector, anticipates the plot of Hudson's later and more famous novel, Green Mansions.
Output: That girl that Smith falls in love with looks how old?