The Star Trek spin-offs always ended in grand fashion, beginning with The Next Generation’s “All Good Things”. The original series’ final episode almost didn’t air! It was pre-empted because former president Eisenhower died, and didn’t air until June 3, two months later in a new time slot. Sure, now you fix the death slot, when you had one episode left and it didn’t matter! Given what we got, they should’ve just left it unaired.
In this episode, we meet Janice Lester, a feminist Starfleet officer who blames Starfleet’s “glass ceiling” for preventing her from having a Starship of her own. That’s my first problem with this episode–how are we to believe that Roddenberry’s future is so great when this form of discrimination still exists? Then again, considering how unstable Lester is, maybe I’m falsely sympathizing. The Enterprise is answering a distress call from Camus II, where she is participating in an archaeological expedition. There are only three survivors, including herself and Dr. Arthur Coleman. All of them are suffering from radiation poisoning, which may explain Lester’s instability.
While McCoy and Spock tend to the other survivor, Lester hatches her plan for revenge. She traps herself and Kirk inside a device and swaps her persona with Kirks: Kirk is now in Lester’s body, and Lester is in Kirk’s. (Note: In reviews I’ve seen of the episode, Kirk is referred to from this point on as Kirk-in-Lester, and Lester as Lester-in-Kirk. This is too awkward for me, so I won’t be doing that for simplicity’s sake.) Lester tries to strangle Kirk, but Spock and Bones stop her. She orders the landing party to return to the Enterprise. Once in sick bay, Lester places Kirk in Coleman’s care, despite Bones’s protests. Bones’s protests are justified because Coleman was ruled incompetent to serve on a starship by the surgeon general. Lester threatens him with demotion, but McCoy is unmoved.
Once they’re alone, Lester and Coleman do the villain-reveling-in-victory-too-early cliché. Lester is finally captain of a starship, while Coleman can finally serve as a medical officer. To further her plans, Lester has Coleman sedate Kirk. Spock is the only one who suspects anything because Lester ignores their current mission in order to drop off Kirk at the Benecia Colony. He objects because the Colony’s facilities are too primitive to care for Kirk. McCoy uses this opportunity to usurp her authority and insists on a medical exam, which Lester passes. Kirk escapes, but Lester slaps him until he’s unconscious, despite McCoy’s objections. Lester then orders Kirk to be put into isolation.
Spock persuades the guard to let him see Kirk, and he performs a mind meld, allowing him to discover the truth. Lester accuses Spock of mutiny and orders a court martial by trial. This only leads to more “mutinies” and some bad acting, even by William Shatner standards. (he tends to ham up “evil Kirk”.) Lester realizes the only way for her plan to work is to kill Kirk, and she has Coleman inject Kirk with a neurotoxin, but it instead reverses the swap.
This isn’t just my opinion, but the opinion of many Trekkers, in fact the episode is hated almost as much as the infamous “Spock’s Brain”. (Yes, we’re going to cover that one. You’ve been warned) Shatner puts on his worst “Evil Kirk” performance (although in his book Star Trek Memories, he admits that he was suffering from fever during the performance, so maybe it’s not all his fault). The episode has no redeeming qualities and should’ve just remained buried. The episode that aired before it, “All Our Yesterdays”, would’ve been a far better finale.
Aspie Catholic 
Much as I still take issue with the way with Spock was treated in “Spock’s Brain”, this is probably the worst TOS episode in technical terms, and the saddest, most unfortunate way to end TOS’ run 😦
What’s even worse is that it was wasted potential. I think if Lester was written in a more sympathetic way, I might’ve been able to overlook the idea that in that future, the “glass ceiling” would still exist. Especially since years later, we’d have Katherine Janeway on Voyager.
In my opinion, this is one of the best episodes of season 3. I think Shatner was perfect portraying Janice Lester in Kirk’s body. I loved the way Spock did the mind meld and discovered “Janice Lester” was telling the truth, and how the bridge crew wouldn’t follow “Kirk’s” orders. Kirk in Lester’s body was never given the neuro shot. The transference was weakening. I wonder if the author of this article hadn’t seen the episode in a while. He should have watched it right before writing this article. Back to the episode. This is such an interesting episode. It is “fascinating” from the start to the finish. It also goes along with the idea that humans really do have a soul. How else would the machine be able to exchange the consciences of Kirk and Lester? It must transfer the souls. The ending of the episode is also perfect for the end of the series. The final words, spoken by Kirk, were; “if only, if only”. Which I interpret as meaning, if only the powers that be hadn’t cancelled this amazing series. What more perfect ending could there be?