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Kirk, Spock, and McCoy are trapped in a planet's distant pasts, where Spock finds love with an exiled woman.




The Enterprise orbits Sarpeidon

A star shines with a reddish glow, and will soon destroy the planet orbiting it, Sarpeidon, in a supernova. Captain Kirk plans to go with a landing party to warn the inhabitants that their sun (the star Beta Niobe) is about to destroy their planet.

Kirk materializes with Doctor McCoy and Spock in a room. They find the building is empty except for Mr. Atoz, a librarian in this library. They soon meet several of his replicas.

Act One[]

Atoz tells the USS Enterprise's landing party that the inhabitants knew about the impending supernova. They are safe by traveling into the planet's past, using a time portal called the atavachron. Kirk and McCoy are intrigued by the library and start exploring the small discs which archive the planet's past. Kirk is viewing a disc of an era of horse-drawn carriages, when people wore the style that resembles 17th century England on Earth. McCoy is viewing one detailing the Sarpeidon Ice Age. Spock offers to evacuate Atoz, but Atoz explains he will join his wife and family when the supernova comes. Suddenly, Kirk heard a scream so he runs toward the adjoining room... the atavachron repeatedly flashes and instantly he stands by a brick wall during the era of the disc that he saw. Spock and McCoy immediately follow after him, and appear in a windy blizzard on frozen wasteland. They realize that they are in the era five thousand years before, when this planet was in an ice age.

Kirk sees a man push a lady, then another fop pushes her. He runs to stop this evil, just as one raises a fencing sword to slash her. He grabs the arm of the murderer. The other draws a sword, so Kirk duels with him. When Kirk wins, the two men flee, and Kirk discovers that the woman is a thief.

Kirk looks back to the brick wall and cannot find the entrance back to the library.

Act Two[]

Sarpeidon prosecutor


Kirk goes to the wall from which he had emerged and is able to talk to McCoy and Spock, but cannot get to them. When Kirk is arrested by the authorities for aiding a thief, McCoy and Spock ask him what is going on, and the authorities can also hear the voices. The woman then betrays Kirk and denounces him as a witch, claiming that he and the "spirits" made her steal against her will. Kirk is forcefully taken away.

Meanwhile, Spock and McCoy try to find shelter while stuck in Sarpedion's ice age. McCoy falls down, his hands and face are frostbitten and he cannot feel his feet. McCoy asks Spock to abandon him and find Kirk himself but Spock refuses. Just then, a figure clothed in a fur jacket and hood emerges from the snow and leads them to a heated cave. Spock has McCoy put onto a bed and wraps him up in a blanket. The figure removes its hood and jacket, revealing it to be a beautiful red-haired woman named Zarabeth. While McCoy sleeps, she informs Spock that she has been exiled to the ice age because one of her kinsman tried to assassinate Zor Kahn, the tyrannical leader of her time.

While in prison, Kirk is questioned by the Prosecutor. When Kirk mentions the library, the Prosecutor becomes extremely uncomfortable. At first, he tries to maintain that Kirk might indeed be innocent. But when the guard insists that he heard voices talking to Kirk, he is forced to back off. When Kirk then starts repeating the word "library" to the Prosecutor, the Prosecutor gets flustered and rushes out, saying he wants nothing to do with Kirk.

Act Three[]

Meanwhile, in the ice age, Spock tells Zarabeth that he must find his captain and get back to his own time. He proposes that she join him and McCoy and find the time portal. He will have the both of them immediately beamed up to the Enterprise upon making it to the future. However, Zarabeth tells Spock that the atavachron alters a person's cell structure and that he therefore cannot return to the future, as he will die.

James T

"That's it! That is the portal."

At the same time, Kirk escapes from his cell when he grabs the jailer, who is trying to pour soup into KIrk's cup, steals his cell keys, and knocks him out. Kirk hides the jailer's body to the side of his cell just as the Prosecutor arrives to take Kirk to the inquisition. However, Kirk overpowers him as well. He questions him and comes to realize that he too had also been sent from the future. Kirk threatens to denounce him as a witch as well if he does not help get him back to the library. The Prosecutor then informs Kirk that the atavachron alters cell structure and brain patterns to prepare people for their journey into the past. The Prosecutor had been "prepared" before crossing and cannot return without immediately dying, but when Kirk announces that he hadn't been similarly prepared, the Prosecutor tells him that they must get him back to the future immediately. If not, Kirk can only survive for a few hours in the past. The Prosecutor then leads Kirk back to the brick wall from which he had emerged. The Prosecutor says he cannot go any further and backs away while Kirk steps back into the library and returns to his own time. He meets one of the Atoz replicas, who insists again that Kirk be prepared, and Kirk is forced to lock him in a closet. Another replica appears and Kirk knocks him out. The real Atoz then appears and stuns Kirk with a cylindrical weapon.

Act Four[]

In the ice age, Spock's personality is beginning to change. He falls in love with Zarabeth and believes her when she tells him he cannot go back. McCoy notices the changes in Spock (especially when Spock responds to a typical insult from the doctor by grabbing him by the scruff of the neck and announcing "I don't like that") and guesses that Zarabeth is not being completely truthful in order to keep Spock with her. Spock also begins to notice that he is not himself after he eats meat and enjoys it. However, even with this knowledge in hand, Spock continues and proceeds to tell Zarabeth that she is beautiful and embraces her. While kissing her, he then begins to further emote and smiles.

Meanwhile, Kirk has managed to recover enough from the stun blast to avoid having Atoz wheel him on a flat trolley, which is similar to that used to carry luggage at airports on Earth, back into the atavachron. Only the empty, out-of-control trolley passes into the atavachron and vanishes into the past. Kirk overpowers Atoz and forces him to help him locate Spock and McCoy by trying out various discs in the viewer. McCoy has begun to realize that it is only Zarabeth who cannot return and confronts Spock with this fact. When McCoy also confronts Zarabeth and tries to force her to admit the truth to Spock, Spock grabs McCoy and flings him against a wall with his hand around his neck. McCoy then asks Spock if he's trying to kill him and if that's what Spock really wants. Spock angrily asserts that this is impossible for him to be acting like this because he's a Vulcan. McCoy reminds Spock that the Vulcan he knows won't exist for another five thousand years, and then asks Spock what's happening there at this very moment. Spock remembers his ancestors at that point were warlike barbarians and McCoy tells Spock he's reverting to the ways of his ancestors, five thousand years before he was born. Spock says he has lost himself and does not know who he is anymore. He then asks Zarabeth if it's possible for them to go back. She says she doesn't know definitively, but McCoy says he's going to try to find the portal because that's where his home and life is.

Spock agrees finally to go with him and Zarabeth accompanies them as well. When they find the area where they had came into the past, and where they once again hear Kirk call out to them through the atavachron, Spock can't bring himself to leave Zarabeth alone in the past. But she once again tells Spock that if she were to cross through the portal, she would immediately die. Kirk calls to McCoy and Spock and tells them they've got to come back, that it's almost time for the supernova. Spock tries to send McCoy on ahead, but McCoy finds he can't go through. Mr. Atoz realizes that they can't come back separately because they had gone through together initially. Finally, Zarabeth turns and leaves them behind and Spock reluctantly goes with McCoy back through the portal. Zarabeth turns around and takes one last look at Spock, with a tear running down her cheek.

Beta Niobe nova remastered

The Enterprise escapes Beta Niobe's supernova explosion

With everyone back, Atoz puts in a disc, pushes Kirk, Spock, and McCoy out of his way, and rushes into the atavachron, heading to join his family in some unknown past era before it is too late. Kirk tells McCoy that Atoz had his escape well planned, and that Kirk is glad he made it to where he was going. He then begins to call the Enterprise to have Scott beam them up. Spock tells McCoy that there's no need to watch him anymore, that he has fully returned to the present. McCoy tells Spock that it did happen though, and Spock agrees, but that it was five thousand years ago and Zarabeth is dead now, dead and buried, long, long ago. On Kirk's communicator, Scott tells Kirk "It's now or never." Kirk orders them to be beamed up and to have the Enterprise taken to maximum warp as soon as they're aboard. The landing party is beamed up and the Enterprise warps out of orbit just as Beta Niobe explodes into a supernova and Sarpeidon disintegrates.

Log entries[]

Memorable quotes[]

"A library serves no purpose unless someone is using it."

- Atoz, to Kirk

"You're a very agile man, Mister Atoz! Just how many of you are there?"

- Kirk, after encountering another Atoz

"We're in a wilderness of arctic characteristics."
"He means it's cold!"

- Spock and McCoy, talking to Kirk through the atavachron portal

"Away! Away, spirit! And let honest men approach."

- Constable, on hearing Spock and McCoy's voices

"We go together."
"You stubborn, thickheaded Vulcan!"

- Spock and McCoy, after McCoy collapses in the snow

"I'm called Spock."
"Even your name is strange."

- Spock and Zarabeth, in the cave

"Do you know what it's like to be alone, really alone?"
"Yes. I know what it is like."

- Zarabeth and Spock

"What is this island?"
"It's called Earth."
"I know no island Earth. No matter. Continue."

- Kirk and the Prosecutor, in Kirk's jail cell

"I heard the spirit talk to him. He answered...and did call it "Bones"!"

- Constable, relating Kirk calling out to McCoy

"Witch!! Witch!! They'll burn ya!"

- Mort, in her cell

"Don't let him doctor you. I'm the doctor around here."
"And known as the worst patient in the entire crew of the Enterprise."

- McCoy and Spock, to Zarabeth

"Now you listen to me, you pointy-eared Vulcan!"
"I don't like that! I don't think I ever did, and now I'm sure!"
"What's happening to you, Spock?"
"Nothing that shouldn't have happened long ago."

- McCoy and Spock, as he grabs McCoy

"You are beautiful. More beautiful than any dream of beauty I've ever known."

- Spock, after kissing Zarabeth

"Spock, you're reverting into your ancestors five thousand years before you were born!"

- McCoy, on Spock's behavior

"I know I'm going to try, Spock, because my life is back there. And I want that life."

- McCoy, on returning to the portal

"And she is dead now. Dead and buried. Long ago."

- Spock to McCoy, on Zarabeth

Background information[]

Production timeline[]

Syndication cuts[]

During the syndication run of Star Trek, no official syndication cuts were made to this episode. However, several local television stations would often edit extended bits of dialogue in order to allow for more commercial breaks. This included:

  • Atoz expressing regret at Kirk wanting to know about "recent history", stating that there was no great demand for such information.
  • A longer scene where the lawman identifies Kirk as the "Mort's henchman"
  • The Magistrate cautioning the Mort that he had no doubt about her guilt and to not falsely accuse Kirk.
  • Mr. Atoz telling Kirk that his actions would get both Atoz and Kirk killed, and that Atoz didn't want to die.
  • Spock's telling Zarabeth that Vulcan was "millions of light years" from Sarpeidon. This allowed for the removal of a glaring plot error, given that this meant the Enterprise would be capable of intergalactic travel. (The Star Trek Compendium)

Story and script[]


Sets and props[]


  • According to the stardate this episode is chronologically the last of the series, even though its production number and air date are earlier than "Turnabout Intruder". This is the last time travel episode of TOS.
  • This is the only episode of any Star Trek series to ever mention a physiological limitation on time travel. According to Mr. Atoz, one had to undergo what he called "preparation" for the era which they would travel to. Failure to do so would result in death after a few hours. Additionally, one could not return to the present era for the same reason (the reason Zarabeth could not accompany Spock and McCoy). It is not known whether this is a result of how the atavachron works, a characteristic of Sarpeidon's atmosphere, or something unique to Sarpeidon's inhabitants.
  • Additionally, this is the only Star Trek story which mentions mental changes to travelers traveling to the past. Spock found himself reverting to the savage nature of the Vulcans of that time period. Curiously, however, McCoy did not find himself reverting to the relative savagery or intelligence of Humans from five thousand years ago. This could be interpreted to mean that Humans have changed little in five thousand years, technology notwithstanding. Or it could reflect Spock's telepathy – we have seen how linked he is to the Vulcan people when the Intrepid was destroyed.
  • TAS: "The Counter-Clock Incident" briefly references the fact of Enterprise's presence near Beta Niobe when it began its supernova explosion.

Remastered information[]

The remastered version of "All Our Yesterdays" aired in many North American markets during the weekend of 21 April 2007. While the episode required very few new effects, the planet Sarpeidon was given a CGI-makeover as was its sun, Beta Niobe. When that star goes nova at the end of the episode, dramatic new effects were inserted into the episode, based upon photographs taken by the Hubble Space Telescope. Initially, when Beta Niobe explodes, Sarpeidon glows before disappearing. And in the remastered version, Sarpeidon crumbles into dust from the supernova blast. [2]

Novelization releases[]

  • Bantam Books published a series of fotonovels, which took photographic stills from actual episodes and arranged word balloons and text over them, to create a comic book formatted story. The sixth installment was an adaptation of this episode, released in May 1978. This was the last of Bantam Books Star Trek fotonovel releases to see internationally translated editions. Translated into Dutch as Al onze dagen van Weleer, the Dutch language edition saw a release in 1979, whereas a German language edition was released in 1980 as Flucht aus der Vergangenheit.
  • The novels Yesterday's Son and Time for Yesterday written by A.C. Crispin are non-canon follow-ups to this episode, concerning a conceived child of Spock and Zarabeth named "Zar."

Video and DVD releases[]

This volume is a three-episode tape to close out the series.

Links and references[]


Also starring[]

Guest star[]





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Unreferenced material[]

Coradrenalin; musketeer; Three Musketeers, The; troglodyte;

External links[]

Previous episode produced:
"The Savage Curtain"
Star Trek: The Original Series
Season 3
Next episode produced:
"Turnabout Intruder"
Previous episode aired:
"The Savage Curtain"
Next episode aired:
"Turnabout Intruder"
Previous remastered episode aired:
"And the Children Shall Lead"
TOS Remastered Next remastered episode aired:
"A Piece of the Action"