The story is based on Clarke's previous Space Odyssey novel series. In the introduction to the Time's Eye, Clarke describes the premise as "neither a prequel nor a sequel" to Space Odyssey, but an "orthoquel" (a neologism coined by Clarke for this purpose, combining the word sequel with ortho-, the Greek prefix meaning "straight" or "perpendicular", and alluding to the fact that time is orthogonal to space in relativity theory). In Space Odyssey, a race of benevolent godlike aliens with highly advanced technology decides to use machines called "monoliths" to travel across space with the intention to ensure the survival chances of intelligent life (including Earth) and "test" and "weed out" species that have no possibility for intelligence.
In the Time Odyssey series, not-so-benevolent godlike aliens start an endless mission to regulate the development of sentient life in the Universe, in order to prevent all other species from harnessing too much of its energy, which would only accelerate the inevitable entropic death of the Universe, thus rendering sentient life impossible at the end of the universe. Consequently, these "Firstborn" are destroying other intelligent species. To preserve a record of these eradicated species, the Firstborn create a new alternate universe containing the species' homeworld in different time periods.