This episode is deeply uncomfortable.
Synopsis
The Enterprise receives a distress signal and tracks it to a duplicate Earth. They beam down to find decayed infrastructure, horrible incongruous architecture, diminishing food supplies, mass unemployment, vagrants roaming the streets... just as it was in the year 2023.
My only guess is that this episode is set on a duplicate Earth for budgetary reasons.
Anyway...
They discover that the people of 2023 were trying to build an immortality virus—though the virology lab seems to be in the US, so they missed that prediction—but instead it killed every adult. The children were blessed (?) with very long childhoods, but once they reach puberty they die.
Children, it turns out, are little assholes. The Enterprise crew who beam down (Kirk, Spock, McCoy, Rand, and two red-shirts) are infected, and the kids steal their communicators because why not?
Miri is a girl on the cusp of womanhood. I imagine that the script intended for Kirk to come across as a father figure, but instead he comes across as an Epstein tourist.
Nonetheless, McCoy manages to make a cure with limited equipment, and everyone lives happily ever after.
Commentary
That synopsis was less coherent than usual for me, because this is a deeply incoherent episode. I don't even know what to say. This is Star Trek does Peter Pan. Peter is an asshole, and Wendy is being used.
Growing up is necessary. It sucks.
Let's sweep this episode under the rug.
I think part of what's frustrating about this episode is, Star Trek is generally so on point with its themes. This episode needed to create a threat for the adults, so they had the immortality virus be fatal for adults. This also means that the kids have a gun to their head: they either act maturely, or they die. Kirk's challenge is just to make the kids understand this, so that they'll settle down for a bit.
This means the story is neither really Peter Pan nor Lord of the Flies, though I still think Peter Pan is a closer comparison. The problem is, Peter Pan requires the children to understand that holding onto childhood forever is a mistake, because they're missing out on life. They have to accept that there's value in growing up. "Miri" just asks the kids, do you want to die?
Similarly, there was nothing the kids could've done if the Enterprise didn't come along, since none of them had medical degrees or advanced computers or access to four hundred years of medical research. The kids needed Starfleet as a deus ex machina if they ever wanted to escape their situation.
This is what I meant by incoherence. The story, the sequence of events that happen, are put together in a way that a viewer can follow them. But, taking the episode as a whole, what's being said?
I don't wanna come across as too harsh to you either. My actual goal in this series is to talk about this stuff. You're absolutely right, that Star Trek spends a lot of time on the issue that seeking eternal youth is stupid; it is, after all, a franchise about adults solving challenging problems by being thoughtful and professional. And the adults of 2023 paid the price for their hubris, but man, what's going on with those kids?