Star Trek All Our Yesterdays 1969 Mariette Hartley

When the planet Sarpeidon is about to be destroyed, by its star Beta Niobe becoming a supernova, Kirk (William Shatner), Spock (Leonard Nimoy) and McCoy (DeForest Kelley) beam down and find it evacuated except for its librarian, Mr. Atoz (Ian Wolfe), tending to his replicas. They are a collection of unusual discs, which play the planet’s history and (to their surprise) allow their users to travel into the past through the atavachron, a time machine, into the periods each was studying on disc. The crew travels 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. He becomes very easily agitated, and is intensely attracted to the political prisoner Zarabeth (Mariette Hartley), who enjoys getting company but tells them return is impossible. Kirk arrives in a Cromwellian period, where he’s arrested and suspected of witchcraft. He soon 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 and Bones in a matter of hours; they must all return to the present and board the Enterprise before the exploding sun destroys the atavachron.