When the planet Sarpeidon is about to be destroyed by its star Beta Niobe becoming a supernova, Kirk, Spock and McCoy beam down and find it evacuated except for its librarian, Mr. Atoz, tending with his replicas a collection of unusual discs, which play the planet's history and (to their surprise) allow their users to travel into the past trough the atavachron, a time machine, into the periods each was studying on disc, but they travel unprepared. McCoy and Spock find themselves locked in a frozen ice age 5,000 years ago, where Spock reverts to the barbaric age of the Vulcans, hence touchy and intensely attracted to the political prisoner Zarabeth, who enjoys getting company but tells them return is impossible. Kirk arrives in a Cromwellian period, where he's arrested and suspected of witchcraft, but realizes the magistrate must be a time traveler like him, and learns not being prepared at molecular level he can return through the time portal, and in fact must do so and contact Spock ... Written by
Did You Know?
There were two highly successful sequel books, "Yesterday's Son" and "Time for Yesterday", both by A.C. Crispin. See more
When in the Ice Age period, Spock starts regressing at the level of his ancestors five thousand years earlier. However, McCoy does not. Behaviorally speaking, humans have remained relatively unchanged over the past 5,000 years, despite our technological advances. The Vulcan people were on the brink of oblivion not because of what they could do technologically, but who they were emotionally. Humans now are similar to humans at the beginning of the Bronze Age, regardless of our technological advances. See more
Captain James T. Kirk
You're a very agile man, Mr. Atoz. Just how many of you are there? We came as soon as we knew what was happening.
Forgive me, sir. It is my fault. I must have miscalculated. Our readings indicated that there was no one here at all.
Of course I know. Everyone on this planet was warned of the coming nova long ago. They followed instructions and are now safe. And you had better do the same.