The text opens with the Time Traveller hosting a dinner party for his friends (the Medical Man, the Psychologist, a Provincial Mayor, an argumentative man named Filby, and a Very Young Man). During this dinner, the Time Traveller does his best to explain the idea of a Fourth Dimension of time to his guests. The guests are unmoved by his argument, which brings the Time Traveler to demonstrate a miniature prototype of his time-travelling invention. The model disappears, presumably forwards into time, but still his guests assume it is only a trick. Frustrated, the Time Traveller shows his guests the full-scale version of his time-travelling machine, which is nearly finished building. He encourages his friends to return the next night to understand how the machine truly functions. The next night, the Time Traveller is late to his own dinner, bloody, ragged, and hungry, finally telling his guests the story of his time-traveling adventures.

The Time Traveller begins his story by describing the sensation of traveling through the fourth dimension, which he compares to falling. He eventually lands his machine in 802,701 A.D. next to an enormous statue of a white sphinx. As he explores this new land, he comes across a civilization called the Eloi. The Eloi are described as appearing consumptive, feeble, androgynous, elegant, and child-like. They survive only on fruit, and live of life of leisure, free from any type of worldly concerns. The Traveller describes his surrounding environment as idyllic, lacking any weeds, but the towering buildings that surround the land are slowly falling into disrepair.

Returning to the area around the Sphinx, he discovers that his time machine is missing! He launches into a frenzy, furious at his inability to travel through time away from his current location. He eventually determines that the machine has been dragged under the Sphinx, and locked away. As he looks for the machine, he comes into contact with the Morlocks for the first time. The Morlocks, living under ground and in the dark, have enormous eyes and small, strong, hairy bodies. After some interaction he escapes the underground tunnels using the light of fire. After some thought, the Time Traveller concludes that the human race has evolved into two different species: the Morlocks and the Eloi. He sees the Eloi as the wealthy bourgeois, supported by the hard work and forceful degradation of the Morlocks, who are meant to represent the proletariat. This is often seen as a commentary of the pitfalls of both communism and capitalism.

The Time Traveller continues to essentially wander through the year 802,701 AD until he comes across an Eloi drowning in the water. In a fit of compassion, the Time Traveller rescues this Eloi, discovers her name is Weena, and they develop an intimate and affectionate attachment. She spends several nights sleeping in the crook of his elbow, and shows signs of distress whenever he is not nearby. With Weena, the Time Traveller finds the Palace of Green Porcelain, which is basically a museum full of dusty artifacts which we recognize from our own time. The Time Traveller gathers three things which he intends to use against the Morlocks as he goes to open the Sphinx and access the time machine: a metal bar, matches, and camphor (a fire starter of sorts).

The two then find their way back underground, to the home of the Morlocks. Weena expresses distress, but refuses to leave the Time Traveller’s side. After some confusion in the darkness, the Morlocks appear to close in on both sides, so the Time Traveller starts a fire with the matches and camphor and defends himself and Weena with the metal bar.  Somehow the two are separated, and Weena is lost in the flames, presumably killed. A forest fire ensues, and the Time Traveller finds himself alone again with the dawn. The next morning, the Time Traveller sees the base of the Sphinx is open, and walks inside. In an attempt at an ambush, the Morlocks surround him. After several moments of high stress fumbling with the machine, the Time Traveller gets it to work, pushes the levers forward, and disappears into the future.

He travels for a long time. He describes the days as becoming longer and the sun becoming larger and redder. He also speaks of intense heat and a thinning of the air. He eventually stops to rest on a beach and describes the water as still; the only life appears to be some green lichen on the rocks. After a moment, he notices enormous crabs all around him, walking towards him. He immediately jumps on his time machine and travels forward again, until he reaches an almost lifeless world. It is silent and light snow is beginning to fall. The only sign of life he sees is a jellyfish-like creature about the size of a football. The sun is slowly disappearing behind the moon in an eclipse. At this point, the Time Traveller has had enough, and he returns to his home time.

Back in his own era, he gets off the time machine and enters the dinner party he had told his companions to come to the night before. Apparently, only a day has passed since he left. His guests (the Editor, the Journalist, Hillyer–our presumed frame narrator, the Medical Man, the Psychologist, and a Man with a Beard) are shocked by his appearance, and even more so by his story. They doubt him, although the Medical Man takes note of the curiosity of the flowers that the Time Traveller brought back, which were given to him by Weena. The guests leave the party and Hillyer talks with the Time Traveller for a moment. The Time Traveller decides that he needs to bring something from the future to prove that the machine indeed does work. The narrator agrees to meet the Time Traveller when he is back from his journey, but he is never heard from again.