"...Why are you looking up my tunic like that?"
While the crew is exploring a new planet, Spock is kidnapped by one of the Plant Alien natives.
The episode was written by Walter Koenig, the only original series cast member to write a televised episode.
This episode contains examples of the following tropes:
- AcCENT upon the Wrong SylLABle: Kirk insists on pronouncing Keniclius' name "Keniculus", even when the person he's speaking with is saying it correctly.
- Call-Back: Since this was produced years before Star Trek II: The Wrath of Khan, this is the first on-screen reference to the Eugenics Wars since Khan was introduced in "Space Seed".
- Dying Race: There are five Phylosians left after the plague that ravaged their species, and they're unable to reproduce.
- God Guise: The Phylosians are very reverent toward Keniclius 5, despite his predecessor having caused all their problems in the first place.
- Healing Hands: Spock's clone revives his original with a mind meld. Because of the difference in scale (the clone is a giant), he uses just one fingertip.
- Inscrutable Oriental: Lampshaded, during an exchange between Kirk and Sulu. Incidentally, this episode was written by Walter Koenig, who played Chekov in TOS and was friends with George Takei in real life:Kirk: Any chance of teaching me that body throw? Could come in handy sometime.
Sulu: I don't know, sir. It isn't just physical, you know. You have to be... inscrutable.
Kirk: Inscrutable? ... Sulu, you're the most scrutable man I know. - Ink-Suit Actor: At least, this was the original intention. Keniclius was made to look like Walter Koenignote , who by this point knew that he wouldn't be a regular cast member for the show, but thought he could make a one-off appearance voicing Keniclius. However, there wasn't enough money in the budget for him to even do that, and so James Doohan voiced Keniclius instead.
- Large and in Charge: Keniclius invokes this principle to a truly insane level—apparently there is no way a galactic peace envoy can be effective unless he's the size of an office building.
- Logic Bomb: Appropriately, Kirk talks Giant Spock into restoring Original Spock with one of these, saying that Vulcan precepts like "Infinite Diversity in Infinite Combinations" are incompatible with killing a man to clone him.
- Plant Aliens: The Phylosians.
- Put on a Bus: Spock's clone stays behind to help the Phylosians.
- The Remnant: The original Keniclius was doing biological experiments back during the Eugenics Wars. He fled to space and made clones to carry on his work.
- Sdrawkcab Name: The retlaw plant which hurts Sulu was named after the episode's author, Walter Koenig.
- Well-Intentioned Extremist: Keniclius is doing what he deems necessary to save a galaxy that he thinks is still torn apart by intra- and interspecies wars. Once he's provided evidence that this is no longer true, he backs down.
- You Are Number 6: The giant they meet is Keniclius 5, the fifth (enormous) clone of the original.
- Your Size May Vary: The size of both Keniclius and the giant Spock tends to very from anywhere between five and ten times the size of the regular characters.
