Plot
In 1899, Dr. Alexander Hartdegen is an inventor teaching at Columbia University in New York. Unlike his friend David Philby, Alex would rather do pure research than work in the business world. After a mugger kills his fiancée Emma, he decides to build a time machine that will allow him to travel back in time to save her. After completing the machine in 1903, he travels back to 1899 and prevents her murder, only to see her killed again when a carriage frightens the horses of another vehicle.
Realizing that any attempt to save Emma will result in her death through other circumstances, Alex travels to 2030 to discover whether science has discovered how to change the past. At the New York Public Library, holographic librarian Vox 114 insists time travel to the past is impossible. Alex travels to 2037 when the accidental destruction of the Moon by lunar colonists has begun rendering the Earth virtually uninhabitable.
While restarting the machine, Alex is knocked unconscious by debris and awakens 800,000 years later on July 16, 802,701. The Earth has healed, and the human race has reverted to a Stone Age-like lifestyle. Some survivors, called "Eloi", live on the sides of cliffs of what was once Manhattan. Alex is nursed back to health by a woman named Mara, one of the few Eloi who speaks English. He observes the broken moon and realizes that maybe his teachings led to this future, just like Philby said. The same night, Alex and Mara's younger brother, Kalen, dream of a jagged-toothed face and a creature calling their name. Alex informs Mara of the dream, and she tells him they all have that dream. She then notices that his watch is missing. The next day, the Eloi are attacked by ape-like creatures called "Morlocks" who hunt them, and Mara is dragged underground along with several other Eloi. To rescue Mara, Kalen leads Alex to Vox 114, which is still functional after 800,000 years.
After learning from Vox how to find the Morlocks, Alex enters their underground lair through an opening that resembles the face in his nightmare. He is captured and thrown into an area where Mara sits in a cage. Alex meets an intelligent, humanoid Über-Morlock, who explains that Morlocks descend from the humans who went underground after the Moon broke apart, while the Eloi evolved from those who remained on the surface. The Über-Morlocks are a group of telepaths who rule the other Morlocks, who use the Eloi as food and breeding vessels.
The Über-Morlock explains that Alex cannot alter Emma's fate; since her death drove him to build the time machine in the first place, saving her would prevent its construction and cause a grandfather paradox. The Über-Morlock shows Alexander the time machine, returns his watch, and orders him to go home. Alex gets into the machine but pulls the Über-Morlock in, carrying them into the future as they fight. The Über-Morlock dies by rapidly aging when Alex pushes him outside of the machine's temporal bubble. Alex stops in 635,427,810, revealing a harsh, rust-colored sky over a wasteland of active Morlock caves.
Finally accepting that he cannot save Emma, Alex travels back to rescue Mara. After freeing her, he starts the machine and jams its gears with the watch, distorting time. Pursued by the Morlocks, Alex and Mara escape to the surface as the time distortion explodes, killing the Morlocks throughout the valley and destroying their caves and the time machine. Alex begins a new life with Mara and the Eloi, while Vox 114 helps him educate them.
In 1903, Philby and Mrs. Watchit, Alex's housekeeper, discuss his absence in his laboratory. Accepting that Alex has found peace wherever he is, Philby hires Mrs. Watchit as his own housekeeper. As the two privately bid farewell to Alex separately in the laboratory, Philby proudly throws his bowler hat away in tribute to Alex's objection to blind conformity.
