The Enterprise arrives at the planet Ardana to obtain zenite, a rare mineral which they need to combat a botanical plague on another world. Kirk & Spock beam down but find themselves caught in the middle of a class struggle between the intellectual rulers dwelling in a city in the clouds, sustained by some anti-gravity technology, and Troglytes, the miners who mostly dwell in the caves on the surface of the planet, where such items like zenite are obtained. This is essentially a reworking of the elite class vs. the worker class story penned by H.G.Wells in his famous novel "The Time Machine" (filmed in 1960 and later versions). Extrapolating from such a premise of basic inequality, where-in the elites get all the benefits through the sweat of the workers, it proposes that, some time in the past, one race experienced an extreme branching off separation into two, though, scientifically, they are still all the same race. Kirk & Spock see them as the same, simply a division of the rich vs. the poor, but the egotistical intellectuals of Stratos, the hovering city, have come to see themselves, over the centuries, as a different, superior race.
All of this is sort of summed up by Spock's voice-over as he sits in meditation in his guest room on Stratos, as images of various characters from both sides of the issue are transposed over his form. This sequence also kind of reminded me of scenes and voice-overs from the film "Dune"(84) - another variation on depicting royalty vs. poverty in a futuristic setting. It's a fairly exciting episode from the 3rd season, especially when I saw this as a kid, with several hand-to-hand struggles, and perhaps with even an increase to the usually-lackluster budget for 3rd season episodes. The episode also does a good job of contrasting the desperate stance and attitudes of the Troglytes (variation of 'troglodyte') when compared to the superior attitudes of the elites on Stratos. On the downside, this episode would have rated at least a couple of stars higher had it adhered to the complex social problems presented. Instead, it's revealed that a gas, released when digging for zenite, causes a retardation to the brains of the Troglytes. This problem is solved with the introduction of gas masks by Kirk, which will, in turn, the conclusion suggests, eradicate the inequality on Ardana. This plot turn devolves the episode to simple escapist sf fare, away from the potentially insightful commentary on cultural inequality.
