The movie opens with a man walking down the street having just left a building in late-Victorian era London. It's wintertime, and the man pulls his coat around himself and hurries across the street. He knocks on the door of a house there, and a woman in late middle age lets him in. There he joins three other men who are sitting around the fire. The man's name is David Filby, and he and the three other men have been invited to dinner by George, who owns the house. He asked them to come over at 8:00 p.m., and it's just now 8, but George himself has yet to arrive. The date is January 5, 1900. The men are clearly unhappy about being kept waiting. A moment after 8, the woman, whose name is Mrs. Watchett, George's maid, enters the room and passes Filby a note. She tells them that George has been missing for several days. The note says that George thought he might be late, and if he was, then she should serve dinner and they could start without him.
They enter the dining room and sit down with their drinks, still complaining about George's absence. The door opens just then and George is there, looking very dishevelled, with noticeable cuts and bruises and torn clothes. He made it only a few minutes late. All the men, plus Mrs. Watchett, are concerned for his welfare, but he insists that he is OK, and he has "all the time in the world". He begins to tell the story of what happened to him. It begins five days earlier, on the night of December 31, 1899, when George and his four friends had been together in the same house, in the parlor that the men had left minutes earlier.
On that evening, George had told them about his experiments, how it was easy to move through the three spatial dimensions, but man had yet to figure out a way to travel through the fourth dimension, time. George hoped to invent a way to do so. He had spent two years working on a device to do so. His friends remain skeptical of his claim. He asks them to witness a demonstration of a small scale model. He opens a box on the table to reveal a machine, which he can hold comfortably in his hands, consisting of a seat, a control panel with a switch in front, and a rotating disk in back, surrounded by a brass railing. His friends think he might be a little nutty when he tells them how it can move not through space, but through time. George borrows a cigar from one of his friends, and bends it and puts it in the little model's seat to represent the man who is time traveling, then, using one of his friends' fingers, pushes the switch forward. The disk on the back starts to rotate, and in a few seconds, the machine fades and vanishes from sight. It is gone into the future, never to return.
George's friends look around for the machine, at first thinking that he had performed a conjuring trick and the machine was simply somewhere else now, but George insists that it had not moved in space, but in time. The machine was still in exactly the same space on the table, but could be far in the future when the table upon which it stood or even the entire house might not exist any more. While George's friends are discussing what they have witnessed, George expounds on his theories and states his intention to take a time trip himself. His friends are concerned, wondering if George's inventing skills might be better put to use advancing the interests of his home country, Great Britain. The Boer War is going badly and the War Office might need some help. Still pondering what has been demonstrated, George's friends leave the house, wishing him a happy new century.
George returns inside and discovers that one of his friends, David Filby, is still there. Filby tells him that he was still worried that George had been behaving oddly and had changed a lot. George tells him he is preoccupied with time because he is unhappy with the time he lives in, with its constant wars and strife. Filby initially thinks that George intends to travel to the past, but George says he prefers the future. Filby can think of all that the machine could do, and implores George to destroy it because the technology is so dangerous. He invites him to come and spend New Years with him, but George declines, saying he'd rather spend New Years alone. Filby asks George to promise him he won't leave the house tonight, and George promises he won't walk out the door. Then he invites Filby to come and bring the others over for dinner on Friday, January 5, 1900, five days hence. Filby leaves and George writes the note that he would read five days later. It's about 6:30 p.m. He wishes Mrs. Watchett a good night and then hurries off to his laboratory.
There is another time machine there, only this one is full-sized, big enough for George to climb into. George examines it for a short time, removes the glass-knobbed control lever for a little tinkering. He lights a candle in the corner and works on the handle for a moment, then returns to the machine and climbs in. Turning on the power switches, he looks down at the control panel which shows today's date, December 31, 1899. He nudges the handle forward slightly, and the disk behind him begins to rotate. After a few seconds, he pulls the handle back to the neutral position and looks around. Nothing seems to have changed, until he notices the clock in the corner. It was after 8 p.m., and the candle he had lit was several inches shorter. Checking his watch in his pocket, he saw that it still showed only a little after 6:30 p.m. It had been in the time machine with him.
George pushes the handle forward again a little further this time, and this time he watches time pass. As he watches, the candle burns down and goes out. The hands on the clock spin around. The sun comes up and moves rapidly across the sky. A snail races across the floor. Flowers open and close with the daylight. The sun goes down and comes up again, all in the time he perceives, inside the time machine, as only a few seconds. He sees people across the street at Filby's department store and sees the female dummy in the window. George notes that he is still traveling slowly and pushes the handle forward a little more, and the time progression outside the machine accelerates. Days pass by rapidly, and George improves his handling of the machine. He slows the machine down in the summer of 1900, and the alternating daylight and darkness slows, George looks across the street and sees the dummy in the department store window dressed differently. Bemused by the changing fashions, George continues to watch the clothes on the dummy change as he continues his journey into the future. Going faster, George watches the seasons change outside his windows instead of just days and nights. He was into the 1910s now. Suddenly, the light was gone - the windows had been boarded up. George brought the machine to a stop in September 1917, and got out to investigate.
His laboratory was dirty and filled with cobwebs, and entering the rest of the house, he found it in the same condition. It had been abandoned for who knows how long. All the furniture was covered in drop cloths, and these were covered in a thick layer of dust. All the clocks in the parlor were silent, since no one was there to wind them or set them. A mouse skittered across the floor. George walks outside, after kicking aside the boards that were covering his door, to see the outside of the house abandoned and neglected, too. A wooden fence had been erected around the house. George went through it and crossed the street, walking towards Filby's store, which was still there. He saw an early automobile, something he'd never seen before in his own time. A man wearing a soldier's uniform got out, and George recognized his friend Filby! Delighted, George began to speak to him. When George mentions Filby's lack of a mustache, Filby realizes that George has confused him with his father. This man is James Filby, who was the infant son of David Filby in George's time. David Filby had been killed in the war (World War 1) which George knew nothing about. George asks James Filby about the house across the street (his own house) and James tells him that the guy who owned it had disappeared around the turn of the century. It had fallen into David Filby's hands, who refused to sell it, thinking that George might return to claim it some day. The house had acquired a reputation as a haunted house. George is dejected and realizes he's out of place, and makes his goodbyes and returns to his own house. He stops outside to pull some of the boards off his laboratory window so he can continue to watch the dummy in the store window.
George returns to the machine, gets in, and heads into the future once more. The house is still neglected and the windows break. He watches the dummy in the window as he speeds through the 1920s and 1930s. Then, in 1940, the room starts to shake. Thinking the machine might be at fault, George brings it to a stop in June 1940, only to discover that the disturbance came from outside. There are airplanes outside (something else he'd never seen before) dropping bombs with anti-aircraft guns shooting at them and fires burning in the distance. He realized that this was a new war, and he pressed on into the future to see how it went. Shortly afterward, his laboratory caught fire and disappeared. His house had been destroyed by a German bomb, and George was out in the open, safe within the time machine. He continues through the 1940s and watches as construction workers build a new large building not too far away. The fashions on the dummy in the window continue to change.
George hears a strange sound and brings the machine to a stop once more, this time in August of 1966. The sounds were air-raid sirens. He gets out of the machine and looks around. The ground that his house once stood on now looks like an urban park. Men and women walk through it in a hurry, urged by men in uniforms to get into the air-raid shelters. He looked out at the street, seeing many skyscrapers in the distance, and Filby's store had expanded to fill a whole block, with a substantial building of its own. Baffled by the commotion, George reads a plaque he finds in the park: "This park is dedicated by James Filby to his father's devotion for his friend George."
The people have mostly disappeared into the underground air-raid shelters. George looks at Filby's store, and just then an aged James Filby wearing a silvery uniform walks out on his way to the shelters. George stops to talk to him, extremely impressed by the growth of the store and the whole city. James just wants to get into the shelters as quickly as possible before the mushroom clouds appear, another phrase George doesn't understand. James suddenly realizes that George looks familiar, and George tells him that he talked to him in the same place, in front of the store, back in 1917 - 49 years earlier. James recognizes him as the same man but how could he possibly have not changed in such a long time? The talk is cut short when the air-raid sirens go off again, and James points to the approaching nuclear bomb and hurries off to the shelter. George lingers outside, then starts to walk back to his time machine, when the bomb goes off. George is far enough away from it not to be incinerated, but the buildings around him burst into flame and fall apart as he watches. London, built brick by brick over two thousand years, is obliterated in seconds. The explosion caused a geological disturbance, and a volcano appeared and lava flowed down the street, destroying anything in its path that had not been destroyed by the bomb. George jumped back into the time machine and escaped into the future before the lava could reach it. The lava cooled around the time machine, forming a casing of stone. George sped into the future, waiting for erosion or other natural forces to wear the rock away.
Thousands of years in the future, the rock eroded and George was once more out in the open, but the bleak, desolate landscape offered no hints that a city or even mankind had ever stood there. He watched trees grow. He could no longer detect changing seasons. Then he saw new buildings going up, but they appeared more primitive than the ones he had left behind. As he sped forward through the centuries, he watched a dome and a tower being built and then fall into disrepair and ruin. Curious once again, George stopped the machine on October 12, 802701. He stopped too fast, and the angular momentum from the suddenly stopped spinning disk caused the machine to spin around and fall over. Shaken but unhurt, George got out, righted it, and set out to explore.
There was a large stone building behind him, with a large metal statue on top that looks kind of like the statues on Easter Island. There are two large metal doors in the building. George knocks on them (clang!) but no one answers, and he cannot open them. George takes the glass-knobbed control handle out of the time machine, just in case, and then goes to explore the forest. The trees are laden with large, delicious-looking fruits, and he finds some more ruins, but he does not yet find any humans. After passing through the forest, he finds the dome he saw earlier. It was neglected and almost in ruins, but it was obviously still in use. It still had functioning doors, and there were tables and chairs and dinnerware inside when he entered.
There were no people, so George left the dome and went back to the forest. Continuing to walk, he at last hears voices in the distance. Finally he comes across some people, in a clearing in the forest by the river. All of them were blond-haired, dressed in plain clothes, and fairly young. They were laughing and playing, and George thinks at first that this is the future he had hoped for, where war, work, and hardship had been left behind in the past. Then he spots a woman in the river, obviously in distress. She is not able to swim through the current and seems to be in imminent danger of drowning, yet none of the other people do anything to help. They just look. George runs into the clearing and urges them to take action, then dives into the river and rescues the woman when they do nothing. The people just look at him.
The people get up and walk away, laughing and chattering, and they go to the dome that George left not long earlier. George follows them but lingers on the stairs. The woman he saved comes back to talk to him. She talks softly and slowly and appears to not quite be all there. She seems to think nothing of the fact that none of the other people tried to save her from drowning. She tells him her name is Weena, and her people's name is the Eloi, but she is dumbfounded when he asks her to spell it. The people are illiterate. Weena encourages George to come with her into the dome, because it is getting dark.
Inside the dome, the people are eating the fruits laid out before them on the table. George tries to talk to some of the other Eloi people, but they are exceptionally poor conversationalists. Besides losing written language, he learns that the Eloi have no government or laws, and no one works. The food simply grows without being cultivated. The Eloi seem to have all the free time in the world, but they don't even study or experiment or learn anything. They have lost their human curiosity as well.
George asks an Eloi man if there is any way he could learn about the Eloi culture, such as from books, and the man tells him that there are indeed books. He shows George the books, which are in a dusty, long-neglected room in the back. George picks up a book which appears to be in terrible shape, and he discovered how terrible it is when he opens it to find the words faded to near-illegibility, a page crumbles to dust when he tries to turn it, and the whole book fragments to pieces in his hand. The books had been left to rot untouched for so long that he is able to put his fist through a whole shelf full of books, reducing them to powder. George now realizes how repulsive this culture is: although they had no more war and hardship, they had also lost everything that made life worthwhile over the centuries - knowledge, science, mathematics, philosophy. He returns to the dome, voices his disgust and intends to return immediately to his own time. Weena looks at him as he leaves the dome.
George returns to the stone building, and discovers to his horror that the time machine has gone! There are grooves in the dirt leading to the metal doors of the stone building. Apparently, someone or something dragged the machine inside. George is now trapped in the future. He picks up a rock and pounds on the doors, but they do not budge. Looking for another way in, George walks around the building and sees something moving in the bushes. It retreats when he lights a match. He sees another shape moving around, goes to check it and discovers that it is Weena! She had followed him to try to get him to come back to the dome. It was dangerous to be out at night. George asks Weena how to get inside the building behind them, and she says no one can get inside except the Morlocks. The Morlocks provide the Eloi with their food and clothing, but the Eloi must obey them. Eloi insists that they retreat to the safety of the dome, but George prefers to keep trying to get into the building, and he starts gathering wood for a fire to keep the dark at arm's length. She finds a wild flower, of a type unknown to George, and gives it to him.
George begins to talk to Eloi about when he came from. Standing in front of the building, they are in the exact same place that George's house used to be eight hundred thousand years earlier. While he is talking, one of the shapes George saw earlier emerges from the bushes and grabs Weena. George runs after her and beats off the attacker, but doesn't get a good look at it. It was a Morlock. George gets the fire going, and Weena reaches out to it curiously; she has never even seen fire before. He tells her that she seems to have a few of the traits that had been largely lost, as she tried to help him by coming out of the dome. Yet she tells him that her people have also lost the concept of past and future. George thinks that he has landed in one of Man's many Dark Ages and wonders if he can help lead the people out.
In the morning, George still could not open the doors to the stone building, but discoveres several artificial holes in a nearby field. He can dimly hear machines pounding on in the darkness below. Weena knows that they are another entrance to the Morlock world because some talking rings told her. George asks her to show him the rings, and she leads him back to another dusty museum area. There is a table with some rings, and George asks Weena for a demonstration. Weena spins a ring on the tabletop, which glows underneath the ring and a voice begins to speak - apparently, this is one of man's many later technologies that had been developed and then forgotten. The voices were old news reports. The ring spoke about the end of a 326-year war, which had ended only because so many people had been killed that there were not enough people left to fight and nothing left worth fighting with or for, and pollution was rapidly killing off the survivors. George spins another ring, and this recorded voice is that of one of the last people to have a past. It described that some of the few stragglers left over from the war had gone underground to survive, and a few others had remained on the surface. George learned that those had gone underground became the Morlocks, who fed and bred the Eloi like cattle and took them in to an unknown fate periodically.
Trailed by Weena, George returns to the field with the holes and begins to climb down a rusty ladder inside. Just then, a wailing sound begins and some rods emerge from the top of the stone building. It sounds just like the air-raid sirens during the wars. Weena appears to go into a trance and wanders off. George climbs back out of the hole to see what was going on, and sees scores of other Eloi walking like lemmings out of the dome, through the forest, towards the stone building. He can't get their attention, and he can't find Weena. Continuing through the forest, he spots her and grabs her, but she just looks blankly at him and continues walking. Closer to the building, the sounds of the siren are deafening. The metal doors to the building are wide open and the Eloi are walking through them into the building. George runs forward toward the building, but as quickly as it started, the wail of the siren ceases, the rods drop back into the building, and the metal doors close - with Weena inside and George out.
The Eloi who had not yet reached the doors suddenly came out of their trance, like they had just been woken up, and start wandering away. But none of them know what happens inside the building. They only know that it is now "all clear" - a holdover from the old days. They only know to hide underground when the sirens go off. George tries to explain to them that all the wars, sirens, all clears, and the people who had participated in them were long dead, but they don't seem to understand anything except that it was now all clear, and they don't seem the least bit perturbed that people who enter the building are never seen again. Frustrated and determined to save Weena, George returns to the field with the holes and climbs down. The Eloi on the surface look down at him.
Underground, George can hear the machinery, and finds some wood and tinder to make a torch, but doesn't light it yet. He explores the underground chambers and sees some of the machines. Some figures move around in the background - Morlocks - watching him, and he is aware that something is there but doesn't see them yet. Wandering into the next room, George sees human skeletons, and miscellaneous human bones sitting in bowls and on plates. It's a dining room, and he now sees that the Morlocks have turned cannibal and the Eloi who enter the building became dinner.
George returns to the main underground room and explores a little more, then he sees a Morlock clearly for the first time. It is driving the complacent Eloi with a whip in their walk to the slaughter. George spots Weena in line, and grabs her and removes her from the line and tries to wake her from her trance. A male Eloi wakes up and follows. George's cover has been blown and a Morlock attacks him from behind with the whip, and he drops his stick. George is able to wrest the whip from the Morlock's grasp and begins attacking it. Several more Morlocks joins the fray, and George must retreat.
Remembering their fear of fire, George lights a match, and the Morlocks retreat, but the match goes out soon and they can advance again. One of the Morlocks tackles him while he is fumbling with the matches. He is able to escape and go over to where the stick landed. He tries to light it, but he's running out of matches. Weena runs over to him and gives him a piece of cloth torn from her dress to burn. George puts it on the end of the stick and lights it. Now he has some fire to drive the Morlocks back with. While George is keeping the Morlocks at bay, the Eloi start moving towards the stairs, but then he drops the torch and he is reduced to fighting with his fists. The Morlocks are not very effective in the melee, but there are a lot of them. Weena tries to grab the torch, but she is once again grabbed by a Morlock. George saves her once again, punching the Morlock repeatedly. Another Morlock charges him and this time seems to get the upper hand. One of the male Eloi, having just seen the fight, makes a fist for the first time in his life and imitates George, attacking the Morlock and knocking it out.
George sees the torch guttering and there are more Morlocks still. He grabs it and sends the remaining Eloi up the stairs and follows them, protecting their rear from being followed. The Morlocks try to follow but they must keep a respectful distance from the fire. On his way up the stairs, George passes some flammable liquid and lights it with the torch. The Eloi find more Morlocks blocking their path going up the stairs, but they are able to knock them off the stairs into the fire. Soon the fire spreads to the machines on the floor. The Eloi reach the bottom of the ladders and begin to climb out of the holes, which are already belching smoke. Urged by George, they gather up more dead branches and drop them down into the holes to add fuel to the fire. There is a secondary explosion and one of the walls around the holes falls in. George and the Eloi run to the river, and then there are more explosions underground and the entire chamber and the ground on top collapses into the hole.
The Morlock underworld and the danger it presented had been destroyed, but so too was the shiftless lifestyle of the Eloi as livestock. Yet George was still trapped. He talks to Weena again, and she asks him if he is unhappy that he has to stay where he is. He still wants to return home and tell his own people what he learned. He realizes he doesn't fit in in the future. Weena is interested in seeing George's time and wonders if he has any girl-friends there. He doesn't, but he has his male friends, and his 62-year-old maid. Weena obviously likes him. Their chat is interrupted by the other Eloi, who race into the clearing to draw their attention to the stone building. It too is in flames, and the doors are wide open. The time machine is just inside. George is overcome with joy and pulls the glass-handled control stick out of his pocket. He runs forward to the machine and calls for Weena to join him, intending to take her home with him. But once he is inside, the doors close again with a metallic "bong!" and he can't open them from the inside, either. Worse, a few surviving Morlocks are coming up the stairs out of the conflagration below. George climbs into the machine but still has to beat off the remaining Morlocks as he gets the machine started. He continues forward, into the future, and watches the dead Morlock on the floor rot to a skeleton and then to dust. Realizing that he's been about as far into the future as he cares to see, he reverses the direction of the control stick, sending the time machine hurtling back into the past. Exhausted, he leans back in the machine as the time passes in reverse rapidly backwards. He slows the machine as it finally reaches the early twentieth century, finally bringing it to a stop on January 5, 1900, the night he invited his friends over to dinner. He's back when he started - the only difference is he and his machine are outside in the garden now, instead of in the laboratory where he left. He has to break into his own house just as a distant clock tower chimes 8 p.m. Battered from his fights with the Morlocks, he stumbles into his house to greet his guests.
After he has finished telling them his story, it's after 9 p.m., and his friends still don't believe him. They think he's a great storyteller, though. George doesn't know how to make them understand, but he reaches into his pocket and finds the flower that Weena gave him. Handing it to David Filby, he challenges him to match it to any species known in the present day and tell him how he obtained it in such condition in the middle of winter. He is stumped.
His friends get ready to leave, telling George he appears exhausted, as he no doubt is. As before, Filby lingers to talk to him. George makes his goodbyes to him, and they sound final, as if he suspects he might not see him again. Filby talks to the other men in the carriage, and he sounds like he almost believes the story himself. Then as the carriage drives off, Filby returns to the house to check on George. George is dragging the time machine through the falling snow back into the laboratory. While Filby is looking for George, he hears the time machine being revved up. He reaches the laboratory with Mrs. Watchett but not in time to see George disappear bound for the future once more. However, he does see the open doors and the tracks made by the time machine's brass runners.
Suddenly, Filby realizes that it's true as the pieces of the puzzle fall into place. George had built his time machine in the laboratory, and it traveled through time but not through space. When he had returned home, it appeared in the garden, but this was only because the Morlocks had moved it a few dozen yards into their building in the far future. The patch of ground occupied by the laboratory would eventually be just outside the stone building, and the place where the garden was would be just inside it eight hundred thousand years in the future. George had dragged the machine back to its original location so that when he returned to the future, he would be outside the building and those impenetrable doors, outside, in the last place he had seen Weena.
Returning to the parlor, Filby realizes that George would probably have taken something with him if he intended to help the Eloi rebuild their culture, and sure enough, three books are missing from the shelves. They don't know which books. Filby and Mrs. Watchett wonder if George will ever return, and if so, when, but Filby realizes that George has, quite literally, all the time in the world. He leaves, and Mrs. Watchett turns out the lights.