What it’s mainly about

How do you deal with a mystery creature that interferes with important economic work and worse yet, kills the workers? Especially when the home territory of this creature is a cave with many tunnels and pitfalls? In an evolving hunt, Kirk and Spock each change their minds about what sort of threat they are up against, and whether to kill the creature or save it. Of course, the miners whose lives are at risk can think of only one solution….

Why it’s awesome

A major theme of TOS (the original Star Trek) is that our dynamic duo of Kirk and Spock never accept that they can’t find a way out of trouble. If what is seen as “possible” won’t work, they are willing to try the impossible. In this drama, though, they have different ideas about the possible and the impossible, and the whole episode shows them trying (successfully) to influence each other’s view. Kirk is concerned about Spock’s safety, and Spock reciprocates by being just as concerned about Kirk’s. In this episode we see that the high functioning of each man is magnified when they work together — and they can’t be defeated.