The book's protagonist is a scientist and amateur inventor living in London who is never named; he is identified simply as The Time Traveller. Having demonstrated to friends using a miniature model that time is a fourth dimension, and that a suitable apparatus can move back and forth in this fourth dimension, he builds a full-scale model capable of carrying himself. He sets off on a journey into the future.
His journey takes him to the year A.D. 802,701, where he finds an apparently peaceful and pastoral society. Upon arrival, he meets a small human people who name themselves the Eloi. The Eloi live in small communities within large and futuristic yet dilapidated buildings, doing no work and eating a frugivorous diet. The land around London has become an untended garden filled with unusual fruiting and flowering plants. The landscape is dotted with large and dilapidated structures, all clearly no longer used save as sleeping areas for the Eloi. There is no evidence of active agriculture or technology, of both of which the Eloi seem incapable.
The Time Traveller is greeted with curiosity and without fear by the Eloi, who seem only vaguely surprised and curious by his appearance and lose interest rapidly. He disables the time machine and follows them to their commune and consumes a meal of fruit while trying to communicate with them. This proves somewhat ineffectual, as their unknown language and low intelligence hinders the Time Traveller from gaining any useful information. With a slight sense of disdain for his hosts' lack of curiosity and attention to him, the Time Traveller decides to explore the local area.
As he explores this landscape, the Time Traveller comments on the factors that have resulted in the Eloi's physical condition and society. He supposes that the lack of intelligence and vitality of the Eloi are the logical result of humankind's past struggle to transform and subjugate nature through technology, politics, art and creativity. With the realisation of this goal, the Eloi had devolved.
With no further need for technology, agriculture, or innovations to improve life, they became unimaginative and incurious about the world. With no work to do, they became physically weak and small in stature. Males, generally being breadwinners and workers in former times, have particularly degenerated in physique, explaining the lack of dimorphism between the sexes. The Time Traveller supposes that preventive medicine has been achieved, as he saw no sign of disease amongst his hosts. With no work to do and no hardships to overcome, society became non-hierarchical and non-cooperative, with no defined leaders or social classes.
The fact that there was no hardship or inequalities in societies meant there was no war and crime. Art and sophisticated culture, often driven by problems and aspirations or a catalyst for solutions and new developments, had waned, as no problems existed and there were no conceivable improvements for humanity. He accounted for their relatively small numbers as being due to the implementation of some form of birth control to eliminate the problems of overpopulation. The abandoned structures around him would suggest that prior to these achievements, the population had been larger and more productive, toiling to find the solution that would make the new utopia a reality.
