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?
Scotty's voice is heard over a communicator, but he is never seen in this episode. See more
When Spock and Zarabeth are talking, Spock turns to see McCoy standing at the cave entrance and McCoy says, "You've been dishonest with me, Spock," but his lips don't move. See more
What are you called?
I'm called Spock.
Even your name is strange.