When time travel was discovered in the 24^th century, it became apparent that events could be manipulated both in the past and the future. The responsibility to make corrections and alter time fell under the purview of the Eternals, a group comprised of Computers, Life-Plotters, Technicians, Maintenance, Timers, and Cubs. The Computers are the highest-ranking members of Eternity and form the Allwhen Council.

The eldest among them, Computer Twissell, takes under his wing a prodigy named Andrew Harlan and promotes him from Cub to Technician, to the chagrin of certain others such as Computer Finge, who targets Harlan and attempts to thwart him whenever possible. At the same time, Finge takes a young, gorgeous woman named Noÿs from the 482^nd century as his personal assistant, but Harlan suspects there is more to their relationship.

Meanwhile, Harlan is assigned a cub named Cooper and is tasked with training him on Earth history during the “Primitive” age just before time travel. Neither Harlan nor Cooper is immediately certain why the cub was directed by Computer Twissell to study under Harlan.

Despite his attempts to avoid Noÿs, Harlan begins to fall for her and attempts to save her from a change that the Allwhen Council has approved for her century—a change that threatens to remove Noÿs from history and replace her with an analogous version of herself that could be a completely different woman, one with no feelings at all for Harlan.

Desperate, Harlan begins to break the rules of Eternity by smuggling Noÿs to the 100,000^th century, a time that the Eternals have barely explored and mankind seems to be mostly absent from Earth. Knowing that Finge and the council have probably discovered his plan, Harlan sets out to destroy the original discovery of time travel and the formation of Eternity before escaping into the future to be with Noÿs forever.

However, Twissell reveals a secret about Cooper that threatens to undermine Harlan’s machinations. Twissell convinces Harlan to help him undo the damage Harlan caused—until Noÿs reveals an even deeper plot that shakes the foundation of Harlan’s existence…

The End of Eternity is yet another splendid exhibit of Asimov’s remarkable worldbuilding talents. The detail involved in manipulating time and its effects were impressive.

While most of Asimov’s characters in general are afforded little in the way of development and background, at least Twissell reveals a tarnished past that puts him on common ground with Harlan. The tension and pace remain fairly tight once Harlan begins plotting and scheming against Finge and the plot contains sufficient twists to maintain suspense.