Recap: Star Trek S2E20 "Return to Tomorrow"

"Lungs filled with air again. To see again. Heart! Pumping! Arteries! Surging, with blood again. To feeeeeeel again. After half a million years..... to be again."
The Enterprise's mission leads them to uncharted territory, hundreds of light years beyond the territories explored by any Earth ship, pursuing a mysterious signal that turns out to originate from a world dead half a million years, sent by an alien that calls itself "Sargon" and begs the Enterprise for assistance.

It turns out that Sargon is one of only three aliens who survived the cataclysmic war that destroyed the planet millennia ago, and only at the cost of secluding their mental energies inside of orbs and forsaking their physical forms. Sargon begs with the Enterprise to allow the three of them to temporarily borrow the bodies of three of the Enterprise's crew, that they can have bodies long enough to employ their hyper-advanced technology and create robot bodies to inhabit instead.

After much deliberation, Kirk, Spock and Dr. Mulhall agree to become the hosts for the three aliens. Unfortunately, Henoch, the alien who chooses Spock's body, decides he would rather keep an existence of stolen flesh and blood, and makes plans to sabotage Sargon's plan by indirectly killing Sargon and persuading Sargon's wife, Thalassa, to side with him.

This episode provides examples of

  • Agony Beam: Thalassa and Henoch both use their mental abilities to inflict pain. Thalassa grows a conscience and stops. Henoch, on the other hand....
  • Atmosphere Abuse: The Enterprise finds a planet whose atmosphere was ripped away by a cataclysm half a million years earlier.
  • Cessation of Existence: Sargon says "Thalassa and I must now also depart into oblivion" before he dies.
  • Dare to Be Badass: Some would call this the franchise's greatest monologue.
    Kirk: 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! You may dissent without prejudice. Do I hear a negative vote?
  • Energy Beings: Sargon, Thalassa and Henoch qualify.
  • Foreshadowing: Henoch's comment about wondering that the Vulcans had not conquered Earth could be an early sign that he's the bad guy.
  • Getting Crap Past the Radar: Nurse Chapel is quite pleased about having had Spock inside her.
  • Gilligan Cut: "You're going to WHAT?"
  • Grand Theft Me: Subverted, as the crew actually let them. They understand that Sargon and Thalassa only intend to do this temporarily, long enough to construct robot bodies to hold them instead. Henoch, unbeknownst to the others, has more permanent designs on Spock's body.
  • Green-Eyed Monster: Henoch has more than a little of this.
  • Kissing Under the Influence: Sargon and Thalassa smooch no less than 3 times while borrowing Kirk and Mulhall's bodies.
  • Large Ham:
    • When Sargon is in Kirk's body, the hamminess is Up to Eleven. Yes, even by Shatner's standards.
    • Nimoy is clearly having a ball getting to play someone completely different from Spock.
  • Our Ghosts Are Different: The G word is never used, but this is essentially what Sargon, Thalassa and Henoch are.
  • Possession Burnout: Possessed bodies have their metabolic and heart rates shoot up to dangerous levels (presumably native to the aliens' original forms); Spock's Vulcan physiology can tolerate it for several hours, but the humans can only take it for a few minutes before risking death.
  • Power Echoes: When the aliens possess humans they gain echoing voices.
  • Psychotic Smirk: Henoch gives a few in Spock's body.
  • Readings Are Off the Scale: Dr. Mulhall announces this while she and Dr. McCoy are scanning Sargon's underground sanctuary.
  • Red Shirts: Two of them are ready to beam down with the landing party, and no doubt breathed a sigh of relief when they didn't beam down after all.
  • Sense Freak: All of the aliens enjoy the sensations of life again after taking human bodies, but none allow it to affect their work, though Henoch does use the fact that their robot bodies will not have this sensory ability to try and persuade Thalassa to side with him.
  • Soul Jar: The spheres that contain Sargon, Thalassa and Henoch function as these. Later, Sargon uses Nurse Chapel as one for Spock's mind.
  • Sufficiently Advanced Alien: Sargon, Thalassa and Henoch, aliens who survived the destruction of his world half a million years ago by becoming Energy Beings of pure thought.
  • Telepathy: Sargon, Thalassa and Henoch are capable of this. Henoch abuses the power to brain wipe Chapel.
  • Your Mind Makes It Real: Sargon used his abilities to make McCoy believe he loaded a hypo full of poison so that Henoch would believe it as well and flee Spock's body after Chapel injected him with it.