Return to Tomorrow (episode)

Telepathic aliens take over Kirk and Spock's bodies.
==Summary==
===Teaser===
The is traveling through a region of space hundreds of light years farther than any Earth starship has ever explored. A great, ineffable intelligence has activated her distress signal relays, giving her strong readings yet remaining invisible to her sensors. The crew arrive at a destroyed class M planet – much older than Earth, Spock determines, and long dead, its atmosphere ripped away by some cataclysmic event about half a million years ago. A male voice suddenly speaks, referring to the ship's crew as his "children" and asking them to come into orbit. He admits the unpromising state of his planet, and says strangely that he too is dead – and death will be the fate of mankind too, should they choose not to visit.
===Act One=== 
In his captain's log (Stardate 4768.3 – see below), Captain Kirk states his intention to risk contact; Lieutenant Uhura tells him that the entry will not reach Starfleet for three weeks due to the Enterprises distance from known space. Spock's science station probes touch the mysterious planetary speaker, named Sargon, who feeds him the transporter coordinates to a chamber more than a hundred miles beneath the surface. In that deep vastness, Spock detects a serviceable atmosphere and presumes that a landing party should fare well enough. Kirk plans to leave him in command, saying that with this many unknowns "we can't risk both of us being off of the ship." But Sargon makes his preferences plain by cutting the ship's power completely until Spock is added to the landing party. Kirk now asks Spock to accompany him and leaves Lieutenant Sulu in command of the Enterprise.
In the transporter room, Dr. McCoy, security officers Lemli and Leslie, and Lt. Commander Ann Mulhall have reported for beam-down. Mulhall, an astro-biologist seconded to the operations division, is unknown to Kirk; it turns out that her orders to join the landing party came from Sargon himself. McCoy is apoplectic when he hears Spock's revised approximation of the thickness of solid rock through which the party is to be transported: 112.37 miles. The landing party enters the transporter chamber and take their places on the pads as Sargon announces that he himself will operate the transporter controls. The announcement startles McCoy who has yet to enter the chamber himself, but after Kirk stating to him about "staying behind," McCoy takes his place in the remaining open pad in the chamber and have a "medical look" at who or what Sargon is. Once energized, only Kirk, Spock, McCoy, and Muhall shimmer, and vanish as the two security officers' pads fail to activate – another one of Sargon's surprises. 
Deep underground, the Enterprise landing party materializes in a sort of holding area. After the transport is completed, Spock notices that the security guards have not beamed down with them and the Enterprise contacts Kirk. Scott explains that the men are still with him in the transporter room, and still sounds concerned about the landing party's safety when he says that he says that he does not like what is going on, in spite of Sargon's powers to allow contact with the ship and beaming the landing party through much solid rock. Meanwhile, Spock finds that the walls date from the time of the cataclysm and are made from the strongest, hardest material he has ever come across. Mulhall discovers the atmosphere is only slightly different from that aboard ship. 
A chamber opens and the unguarded party enter to discover Sargon – energy without substance, matter without form – housed in a glowing spheroid shell. He gives his guests a little history lesson: 6,000 centuries ago, the humanoids of this planet were spacefarers. They colonized throughout the galaxy. Sargon speculates that a Human creation myth were perhaps two beings of Sargon's race. Mulhall objects to this idea, but Spock picks up on it, saying it might explain away some elements of Vulcan pre-history.
But 1,000 centuries after the colonial heyday came the ultimate conflict. Possessed of minds "infinitely greater" than the landing party's, having goals beyond their comprehension, Sargon's race fought a superwar, unleashing powers to which even nuclear war pales in comparison. And so the masters of the galaxy all but exterminated themselves, and their homeworld for half a million years has lain dead. 
Calling Kirk his "son", Sargon exchanges places with him, taking the captain's body from him and storing his mute mind within the sphere. Sargon is thrilled to have a corporeal form again, and states his intention of using Kirk's, Spock's and Mulhall's bodies.
===Act Two===
Leading the landing party to an inner chamber, Sargon/Kirk shows them ten other spheres ranged in two rows. His wife Thalassa's is the only one still aglow on the lower tier. On the upper, one glows as well – Henoch, of the ultimate conflict's "other side." These essences, too, will require hosts, namely Mulhall and Spock. McCoy complains that Sargon is "burning up" Kirk's body – his heart is beating 262 times per minute. Sargon/Kirk says he and his fellows wish to hold the Human and Vulcan bodies only long enough to build "humanoid robots" with methods and skills "far beyond your abilities." Sargon/Kirk staggers back to the main chamber and, again calling Kirk "son," vacates his body. Kirk's metabolism promptly returns to normal. He says his mind's stay in the receptacle was a "floating in time and space." But the intimate proximity to Sargon during the exchange has affected him deeply: "For an instant we were one… I know him now. I know what he is and what he wants – and I don't fear him." 
In a briefing room back aboard the Enterprise, the landing party is joined by Scott, whose assistance will be necessary in the construction of "android robots." Kirk will not order their participation. With such mechanical bodies, Spock says, Sargon and company will be able to leave this planet and share their technology. The resulting advances for "mankind" would be a great leap of ten millennia. Scott is won over by the prospect of starship engines being "the size of walnuts"; Mulhall says that in the interest of science she must cooperate. McCoy finds it a suspicious coincidence that the bodies of both the captain and first officer are required for the task ahead and worries that to such "giants" the Human crew must be "insects." Kirk compares the undertaking at hand with the first Earth missions to the Moon, to Mars, to Alpha Centauri, and reminds McCoy that six generations ago surgery was done with scalpels and catgut. "Risk…" he concludes, "risk is our business. That's what this starship is all about. That's why we're aboard her." Spock, McCoy, Scott, and Mulhall's doubts about the transference are erased after Kirk's passionate speech.
In the medical lab, McCoy and Nurse Chapel oversee the transference. Thalassa, seeing through Mulhall's eyes, at first looks for her husband in Spock, but Sargon draws her attention "here" – in Kirk's body. She approves of his choice of host, finding it similar to the body he lost in the cataclysm. Henoch is pleased with his own host: the Human-Vulcan hybrid has "strength, hearing and eyesight, all far above your Human norms." Spock's body deals better with the transference too, being "accustomed to the higher metabolism"; Henoch stays in it when the others collapse and for the second time Sargon relinquishes Kirk's body. 
In the pharmacology laboratory, Henoch/Spock and Chapel make up a metabolic reduction formula which, administered from a hypospray at 10 cc/hr, should allow the three cataclysm survivors to function in their host bodies. Chapel notices that Sargon's formula has been doctored and fears for her captain. Henoch/Spock confirms that he intends that Kirk die – so as to finish off Sargon. Henoch/Spock then telepathically establishes mind control over Chapel, touching his middle finger to her forehead, making her forget about what he just said.
===Act Three===
McCoy makes an entry in his medical log (4769.1 – see below): Sargon is now in his third possession of Kirk's body, Thalassa is back in Mulhall's, and Henoch continues to possess Spock's. 
In a science laboratory, Sargon/Kirk and Thalassa/Mulhall are beginning the assembly of their new android bodies. They reminisce, but the lost scenes of their beloved homeworld turn to a cruel reminder of the insensate future that awaits them. Henoch/Spock enters and enjoys the plight of his sorely tempted but morally rigorous opponents. He for one has no intention of relinquishing his host body. Sargon feels the damage he is wreaking on Kirk's inadequately suppressed metabolism, but does not want to worry his wife and soldiers on. 
In the medical lab, Chapel conveys Henoch's bogus metabolic readings to McCoy. Mistaking her evident stress for fatigue, he offers to administer the last few doses of formula to the visitors. Alarmed, Chapel insists she will be up to the task. 
In the shop, Scott cannot see how the technology of the ancient colonizers is going to work in the android bodies, which must "need micro-gears and some sort of pulley that does what a muscle does." A happy Henoch/Spock appears in the doorway and corrects him: comprehend its workings though Scott may not, the android form will surpass his Human strength and agility by 100%. To Thalassa/Mulhall, though, Henoch's upbeat manner rings hollow: the android form will house her for a thousand years – is that not what a prison does? She feels a tremor of revolt against the impending surrender of her humanoid existence. Might a Human body not after all be her due, given all the good she proposes to bring to mankind? 
In the deck six briefing room, Sargon realizes he can no longer ignore the danger to Kirk's body and calls McCoy. Thalassa/Mulhall arrives first and runs the idea of sacrificing Mulhall past her husband. Seeing that the wrongness of the proposition has escaped her, Sargon/Kirk points out the practical difficulties – it will take months, if not years, for the host bodies to grow accustomed to the presence of their essences. She knows that he, too, longs to resume their physical intimacy – the "intertwining" of senses – and kisses him, asking "can robot lips do this?" Fighting temptation as well as Henoch's vapid medicine, he collapses. McCoy and Chapel arrive to find Sargon/Kirk "dead."
=== Act Four===
 
McCoy makes an entry in the medical log (4770.3 – see below). He is sure that Sargon has died, forced to flee the captain's collapsed body, and too far from the receptacle to bring about the exchange of essences. Despite its inhospitality, the vacant body has been brought around in sickbay, its "vital organs now working," as the nurse says. 
 
In the shop, Henoch/Spock works on a male-shaped android body. Thalassa/Mulhall wonders why he bothers, since he clearly doesn't plan to return his present body to Spock. He stokes her revulsion, saying the android form is for her – she can occupy it before it has its female features installed. She cannot bring herself to put her consciousness into the android body.
In the medical lab, Thalassa/Mulhall proposes a back room deal with McCoy: she is able to move Kirk's mind back into the functioning body, but she requires that the doctor connive at her keeping that of Mulhall, "whom you hardly know – almost a stranger to you!" Even for such a return, McCoy cannot leave Mulhall to die. Thalassa/Mulhall threatens him, "we can take what we wish… I could destroy you with a single thought!" She projects fire onto McCoy, but soon her godlike posturing disgusts her, and she realizes that physical existence is seductive and corrupting for her kind. Relieved to witness her integrity, Sargon now speaks: he has been sheltering unsuspected in the very fabric of the vessel. Chapel arrives, having been summoned. Thalassa/Mulhall asks McCoy to leave them, stating "Sargon has a plan." 
In his study, McCoy is alarmed by a series of explosions from the lab. Unable to enter because the door is sealed, he is calling for aid when Chapel exits – with something plainly on her mind. 
Back in the lab, Kirk and Mulhall have regained their bodies. The three receptacles are now charred and burnt out – completely destroyed (it was these McCoy heard exploding). And Spock's mind? Kirk says the loss was "necessary." The urgent task is to terminate Spock's physical form and so put an end to Henoch. Kirk orders McCoy to prepare a hypo fatal to Vulcans. 
On the bridge, Henoch/Spock terrorizes Uhura, who screams. He then sits in Kirk's chair and warns helmsman Sulu not to fight him. Chapel stands beside Henoch/Spock. McCoy arrives with Kirk and Mulhall, whom Henoch/Spock stops short by forcing pain upon them near the turbolift. Henoch/Spock then orders Chapel to take McCoy's hypo, the contents of which are known to him from reading McCoy's mind. Chapel is ordered by Henoch/Spock to inject McCoy, which she prepare to do – but suddenly, she injects Henoch/Spock instead. At first he belittles their attempt, but when he senses the undead and powerful Sargon his instinct is to beg. Spock's body collapses, and Henoch flees — but with no host, android nor receptacle at hand, he is destroyed. Chapel swoons, and Spock stands; he is himself again. When Chapel recovers, she explains that she had been carrying (and sharing) Spock's essence (or katra) which, behind Henoch's back, Sargon had "placed in me." Sargon explains that the hypo, potent enough to "kill ten Vulcans", was a necessary illusion. 
Sargon then requests that he and Thalassa borrow Kirk and Mulhall's bodies one last time so he may hold his wife as a living woman before the couple consign themselves to oblivion "forever". The request is duly granted, and Sargon/Kirk and Thalassa/Mulhall share a final kiss. Thalassa/Mulhall tells Sargon/Kirk that oblivion together does not frighten her, and asks him to promise her they will be together — which Sargon/Kirk does. After Sargon and Thalassa have departed, and Kirk and Mulhall are themselves again; Chapel says, with a teary fond look at Spock, that the couple's final kiss was "beautiful." 
The Enterprise leaves Arret and continues its exploration of space.
==Log entries==
*Captain's log, USS Enterprise (NCC-1701), 2268
*Medical log, USS Enterprise (NCC-1701)
== Memorable quotes==
"One day our minds became so powerful, we dared think of ourselves as gods."
:- Sargon, explaining to Kirk how his people nearly became extinct
"We must have Captain Kirk and you – so that we may live again." 
:- Sargon, in Kirk's body, to the landing party
"They used to say if man could fly, he'd have wings … but he did fly. He discovered he had to. Do you wish that the first Apollo mission hadn't reached the moon, or that we hadn't gone on to Mars or the nearest star? That's like saying you wish that you still operated with scalpels and sewed your patients up with catgut like your great-great-great-great-grandfather used to. I'm in command. I could order this. But I'm not … because … Dr. McCoy is right in pointing out the enormous danger potential in any contact with life and intelligence as fantastically advanced as this. But I must point out that the possibilities, the potential for knowledge and advancement is equally great. Risk … risk is our business! That's what this starship is all about … that's why we're aboard her!"
:- Kirk, convincing Spock, McCoy, Scott, and Mulhall to accept Sargon's offer
"Oh, you are a lovely female. A pleasant sight to wake up to after half a million years."
"Thank you."
:- Henoch, inside Spock's body, and Chapel, after the transference
"I'm surprised the Vulcans never conquered your race."
"Vulcans worship peace above all, Henoch."
:- Henoch/Spock and McCoy, after Henoch comments on the strengths of Spock's body
"I will not peddle flesh. I'm a physician."
" A physician? In contrast to what we are, you are a prancing, savage medicine man."
:- McCoy and Thalassa/Mulhall, as she bargains to keep Mulhall's body
"Spock's consciousness is gone. We must kill his body – the thing in it."
:- Kirk, planning to kill Henoch
"Oblivion together does not frighten me, beloved. Promise we'll be together."
"I promise, beloved."
:- Thalassa and Sargon, inside Mulhall's and Kirk's bodies for the final time
==Background information==
===Production timeline===
*Story outline by John Dugan: early-
*Revised story outline by Gene L. Coon: 
*First draft teleplay by Dugan: 
*Second draft teleplay: 
*Final draft teleplay by Gene Roddenberry: early-
*Additional page revisions by Roddenberry and John Meredyth Lucas: , , , , 
* Filmed: – 
* Score recorded: 
* Original airdate: 
* Rerun airdate: 
* First UK airdate (on BBC1): 
* First UK airdate (on ITV): 
* Remastered airdate: 
During the syndication run of Star Trek, no syndication cuts were made to this episode.
=== Story and production===
*Writer John T. Dugan wrote the original script of this episode after he had read an article about highly sophisticated robots. In his original draft, Sargon and Thalassa continue their existence as spirits without bodies, floating around the universe. However, Gene Roddenberry, who did an uncredited re-write on the script, changed the ending to the aliens fading out into oblivion. This led to Dugan using his pen name John Kingsbridge in the episode's credits. (The Star Trek Compendium)
* Dugan (a devout Catholic) stated: "That line totally went against my philosophy and cosmology, I didn't want to be associated with it. The oblivion idea is Roddenberry's philosophy, not mine. (…) That might be a small thing, but I have a reputation and a philosophy and everybody who knows me knows what I stand for; I certainly don't stand for oblivion in the afterlife. (…) When you write a script, you don't expect to have your "world view" changed by a producer. The rest of Roddenberry's changes were all trivial (…); the big thing was the change in the episode's philosophy." (These Are the Voyages: TOS Season Two, p. 529)
*Dugan's original outline was approved by NBC program manager Stan Robertson on , with the conditions that "the highly cerebral portions of the story would be eliminated and the complex nature of the plot would be materially simplified". (Inside Star Trek: The Real Story, pp. 331)
* Robertson also found Sargon's speculation about "your own legends of an Adam and an Eve were two of our travellers" to be sacrilegious and offending to Christian viewers, hence the line by Ann Mulhall stating that "our beliefs and our studies indicate that life on our planet, Earth, evolved independently" had to be inserted into the script. (These Are the Voyages: TOS Season Two) (Interesting to note that The Twilight Zone episode "Probe 7, Over and Out" in which Adam and Eve are actually revealed to be space travelers, aired on CBS four years prior.)
*The names of the Arret survivors have some cultural connections to Earth. In Greek mythology, Thalassa was a sea goddess. Some Assyrian and Mesopotamian kings were named Sargon. In the Bible, the name Henoch appears several times (sometimes spelled "Enoch" or "Hanoch"), including as the father of Methuselah.
*The name of the planet itself, Arret ("Terra", Earth in Latin, inverted), is never mentioned onscreen, much as Neural, the site of , is also unspoken.
*Joseph Pevney was originally slated to direct this episode; however, he quit the series after , citing the lack of discipline from the actors after producer Gene L. Coon left the show. (These Are the Voyages: TOS Season Two)
*The preview of this episode features a different take of the scene just before Thalassa zaps McCoy. In the preview, Muldaur says, "I could destroy you with one thought!" In the completed episode, she says, "I could destroy you with a single thought!"
* This episode is the latest in any season to feature a new score, albeit a partial one, by George Duning. Parts of the new score would be heard for the rest of the season, including the menacing Henoch cues in and . However, most of this score, notably the love themes, would never be reused in another episode. This sets it apart from other scores, such as those from and , whose themes would be reused extensively.
* Still photos of a smiling Spock leaning against a doorway and a non-canonical image of William Blackburn, dressed as the android were used in the end credits of . That episode was produced before this one, but did not go to air until .
*Blackburn told about his experiences filming this episode. Because of his latex android make-up, he could not eat or drink properly during the 12-hour shooting day and had to consume nourishment through a straw. The white, blank eyes of the android were achieved with him simply moving and holding his eyeballs upwards. (TOS-R Season 2 DVD Special Features)
* In clips from the second season blooper reel, Blackburn peels off his latex coating with glee and is helped by assistant director Tiger Shapiro, who says, "Well, son, you wanted show business. Goddammit, you got it!" In another segment, William Shatner grabs one of the globes and proclaims, "Have no fear. Sargon is here." And in another clip, Shatner jumps a line with DeForest Kelley in sickbay by saying, "I'm fine, Bones." Kelley responds, "Are you all right?" They both crack up laughing. In the next take, they can't even begin to speak before they dissolve into helpless giggles.
*A still image taken from the blooper above, of Blackburn removing the latex android make-up from his head appears in the end credits of . That episode was produced the week before this one and aired two weeks later, on .
===Cast and characters===
* This episode marks George Takei's return to the series after an absence of some months while filming The Green Berets. His last appearance was , which was ten episodes earlier in production order.
* Dr. Ann Mulhall was portrayed by Diana Muldaur, who later played the roles of Miranda Jones in and Katherine Pulaski in .
** As a lieutenant commander, Ann Mulhall has the distinction of being the highest-ranking named female Starfleet character shown in TOS. However, her operations division uniform will be reused for unnamed female background characters in future episodes ().
* James Doohan was the voice of Sargon.
* William Blackburn plays the android that is meant for Sargon's wife. Production photos of his make-up test appeared in the end credits of and .
* Walter Koenig does not appear in this episode.
===Continuity===
*It is unclear how Arretan might have inspired the Adam and Eve story on Earth, especially since they ended their galactic colonization before their civil war. Their colonizing period, which occurred 600,000 years ago, is the earliest estimate for the appearance of Homo heidelbergensis, an early ancestor Humans share with the Neanderthals.
* This is the second time a reference is made in Star Trek about the Apollo moon program, after . Filmed more than a year-and-a-half before the first lunar landing, Kirk rhetorically asks McCoy in this episode, "Do you wish that the first Apollo mission hadn't reached the Moon?" The first manned Apollo mission, Apollo 1 (intended to be a test-flight of the Command and Service Module in Earth orbit only), never flew, since a tragic fire claimed the lives of three astronauts. This happened on 27 January 1967, months before the script was submitted to the production team and a full year before this episode aired. The first Apollo mission in which astronauts orbited – and technically "reached" – the moon was Apollo 8 in December 1968, ten months after this episode aired. However, the Apollo 11 astronauts were the first to "reach" the moon by landing on it in 20 July 1969, after Star Trek was canceled. Kirk's next comments about going "on to Mars and then to the nearest star" seem to suggest that he is referring to the Apollo 11 lunar mission.
===Sets and props===
*One of the fiberglass globes was re-used later as part of the Romulan cloaking device in , and for M-4 in .
*The stand for one of the globes was later turned upside-down and used as a piece of technology on Atoz's desk in .
*This episode features colorful back lights on the Enterprise sets, mostly green and purple, which were not used since the early episodes of the first season.
===Awards and recognition===
*This episode and its writer, John T. Dugan, earned a Writers Guild of America Award nomination in the category Best Written Dramatic Episode in . (Star Trek Inside No. 9)
*Director Ralph Senensky nicknamed this episode "The Huge Ping Pong Balls". Senensky also described this episode as "about which the less said the better". 
===Remastered information===
File:USS Enterprise on patrol, remastered.jpg|The Enterprise patrols unexplored space
File:Arret remastered.jpg|The Enterprise orbits the planet
The remastered version of this episode aired in many North American markets during the weekend of . It featured new effects shots of the Enterprise and a new, more realistic version of Sargon's homeworld. It also included shots of the planet matted into interior viewscreen shots. 
===Video and DVD releases===
*Original US Betamax release: 
*UK VHS release (two-episode tapes, CIC Video): Volume 27, catalog number VHR 2379, 
*US VHS release: 
*UK re-release (three-episode tapes, CIC Video): Volume 2.8, 
*Original US DVD release (single-disc): Volume 26, 
*As part of the TOS Season 2 DVD collection
==Links and references==
===Starring===
* William Shatner as Capt. Kirk
=== Also starring===
* Leonard Nimoy as "Mr. Spock" 
;And
* DeForest Kelley as "Dr. McCoy"
===Guest stars===
* Diana Muldaur as Ann Mulhall
* James Doohan as Scott
* Nichelle Nichols as Uhura
* George Takei as Sulu
* Cindy Lou as Nurse
;And
* Majel Barrett as Christine Chapel
===Uncredited co-stars===
* William Blackburn as
** Hadley
** Arretan android
* Frank da Vinci as Brent
* James Doohan as Sargon (voice)
* Roger Holloway as Roger Lemli
* Jeannie Malone as Nurse
* John Hugh McKnight as command lieutenant
* Diana Muldaur as Thalassa
* Leonard Nimoy as Henoch
* Eddie Paskey as Leslie
* William Shatner as Sargon (body)
* Unknown actors as
** Command crew woman
** Security guard
===References ===
6,000 centuries ago; 500,000 years ago; ability; Adam and Eve; agility; alien intelligence; alloy; Alpha Centauri; answer; Apollo 11; Arret; Arret native; Arret system; artery; astrobiology; atmosphere (aka air); atmosphere report; attitude; bed; best friend; blood; body; body function (aka bodily function); body temperature; "Bones"; bottle; briefing; briefing room; catgut; cc; century; children; choice; class M; coincidence; communication channel; composition; consciousness; conn; Constitution-class decks; contact; coordinates; crisis; danger; day; death; ; ; descendant; diagram; distance; distress signal relay; drawing; Earth; energy; engineer; ; ; euphoria; evolution; experimentation; exploration; eye; eyesight; Fahrenheit; fatigue; fear; feeling; finger; flesh; flower; formula; great-great-great-great-grandfather; God; hailing frequency; hand; ; heart; heartbeat; heart rate; hello; home; host body; hour; Human (aka mankind); humanoid robot (aka mechanical body or android robot); hypo; injection; insect; intelligence; "in time"; jelly; "just a moment"; kiss; knee; knowledge; lake; landing party; landing party duty; legend; liar; life (aka lifeform); ; light year; lip; location; Luna; lungs; machine; Mars; matter; McCoy's great-great-great-great-grandfather; medicine man; metabolic rate; metabolic reduction injection; metabolism; microgear; mile; Milky Way Galaxy; million; mind; minute; miracle; mission; mistake; month; muscle; name; negaton hydrocoil; nitrogen; nuclear age (aka nuclear era); opportunity; order; oxygen; pain; patient; peace; pharmacology; pharmacology laboratory; physician; place; plan; planet; poison; ; prejudice; prison; pulley; question; race; receptacle; rescue; risk; rock; room; Sargon; Arretan; Arretan vessel; savage; science officer; Scots language; search; security guard; sharing; seed; sensor probe; scalpel; science officer; scientist; second-in-command; security guard; sensor; ; size; standard orbit; "stand by"; star system; Starfleet; stranger; strength; subspace radio; subterranean chamber; surface; technician; temperature; thing; thought; thousand; transporter; transporter beam; transporter coordinates; transporter device; transporter room; traveler; tricorder; truth; unconsciousness; ; vital organ; voice; vote; Vulcan; Vulcan prehistory; wall; walnut; war; week; "what in the devil"; wing; wisdom; word; worship; year 
====Unreferenced materials====
alien; illogic; jungle
=== External links ===
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de:Geist sucht Körper
es:Return to Tomorrow
fr:Return to Tomorrow (épisode)
ja:地底160キロのエネルギー（エピソード）
nl:Return to Tomorrow
pl:Return to Tomorrow
Category:TOS episodes