Oh, no, you all know where this is heading, don't you?
The Enterprise crew finds a philanthropist who's been missing for five years, but once he's brought aboard, some strange occurrences go on aboard the ship.
This episode contains the only televised reference to Bones’ daughter Joanna, who had existed in his character outline since Season 2 but twice had her starring episode rewritten and her appearance shelved.
This episode provides examples of:
- The Atoner: After realizing that the Enterprise crew don't deserve to be handed over to the Romulans, Winston attempts a Heroic Sacrifice by turning himself into a substitute deflector shield for the ship. He actually survives, though is taken into custody for collaborating with the Romulans — and even then, Kirk notes that he'll likely get a minimal punishment (if any at all).
- Becoming the Mask: Vendorians have a habit of doing this if they take on a particular form for too long, with it being especially pronounced with the one seen here, who spent a whole year getting to know the original Carter Winston.
- Doppelgänger Replacement Love Interest: At the end, Winston's old fiancée Anne Nored offers to guard Winston, heavily implying she might learn to love the Vendorian as much as he loves her.
- Identity Impersonator: It turns out early on that "Winston" is actually a shape-shifting Vendorian, and during the course of the episode he also uses his powers to impersonate Kirk, McCoy, and an engineer.
- New Powers as the Plot Demands: While one could imagine how Winston could use his powers to become an inanimate object, having him use said abilities to become a deflector shield (an energy field) is pushing it.
The Novelization by Alan Dean Foster gets around this by explaining that the Vendorian turned himself into the component metallic parts that were damaged and thus allowed the deflector shields work instead of becoming the shield itself. - Not Me This Time: When Kirk accuses the Romulans of having planted a Vendorian on-board in order to deceive them into straying into the Neutral Zone, the Romulan commander points out how absurd and convoluted such plan would be even for them, and demands that Kirk surrender. Subverted in the end, however, as it turns out that the Romulans genuinely were responsible for Winston being on the Enterpise, and were banking on Kirk second-guessing himself after coming up with such a ridiculous-sounding theory.
- Objectshifting: A facet of the Vendorian's powers - at one point, he turns into an examination table in the ship's Sick Bay.
- Scotty Time: Subverted; Scotty says that it'll take hours to repair the ship's deflector shield, but it's seemingly restored to working order within minutes. Afterwards, Kirk calls Scotty to congratulate him, but Scotty points out he's still nowhere close to being finished, causing Kirk to realise it was actually Winston.
- Shapeshifting Sound: When the Vendorian changes to another form, there is a brief accompanying sound effect that sounds like a transporter in operation.
- Starfish Aliens: The Vendorians: Orange floating squid-like creatures with six tentacles, five eyes, and can turn into anything they want at will.
- Voluntary Shapeshifting: After the Enterprise crew rescues the philanthropist Carter Winston, he turns out to be a shapeshifter alien called a Vendorian.
