Plot
In 1899, inventor Alexander Hartdegen teaches at Columbia University in New York. Unlike his friend, David Philby, Alex prefers pure research to working in the business world. After a mugger kills his fiancée Emma, Alex builds a time machine to travel back in time to save her. After completing the machine in 1903, Alex travels back to 1899 and prevents her murder, only for her to be killed again in a road accident.
Realizing that any attempt to save Emma will always fail, Alex travels to 2030 to discover if 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 on to 2037, immediately following lunar colonists having accidentally destroyed the Moon, and will render the Earth virtually uninhabitable.
While activating the machine, flying debris knocks Alex unconscious. He 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 cliff sides of what was once Manhattan. A woman named Mara nurses Alex back to health. She is 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. When Alex tells Mara about the dream, she says they all have that dream. She then notices that his pocket watch is missing. The next day, the Eloi are attacked by ape-like creatures called "Morlocks" who hunt them. 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 Vox reveals how to find the Morlocks, Alex enters their underground lair through an opening that resembles the face in his nightmare. He is captured and taken to where Mara is caged. 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 remaining on the surface. The Über-Morlocks are telepaths and rule the lower Morlocks, who use the Eloi as food and breeding stock.
The Über-Morlock confirms that Alex cannot alter Emma's fate; since her death drove him to build the time machine, saving her would prevent its construction and cause a grandfather paradox. The Über-Morlock shows Alexander the time machine, gives back his watch, and orders him to return to his own time. Alex gets into the machine but pulls the Über-Morlock in, carrying them into the future as they struggle. The Über-Morlock dies by rapidly aging when Alex pushes him outside the machine's temporal bubble. Alex stops in 635,427,810 with a harsh, rust-colored sky over a wasteland.
Accepting that Emma cannot be saved, Alex travels back to rescue Mara. After freeing her, he starts the time machine and jams its gears with the pocket 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 educate them.
In 1903, Philby and Mrs. Watchit, Alex's housekeeper, discuss his absence while in his laboratory. Believing that Alex has found peace wherever he is, Philby offers Mrs. Watchit a housekeeper job. Outside, Philby tosses away his bowler hat to honor Alex rejecting blind conformity.
