This is the episode that somewhat undermines my theory that a lot of the cheesiness and campiness of the series was unintentional. Roddenberry and company get very serious in Patterns of Force, and understandably so--this is the episode about Nazism.
Nazism is broached through a very common theme for the series--an alien culture has been corrupted by an outside force. In this case, as in many others, the outside force was a previous explorer from the Federation, one who chose to ignore the Prime Directive of non-influential interference.
For most of the episode, Star Trek doesn't have anything very unprecedented to say about Nazism. It's a fairly literal presentation/examination, with a race from a neighboring planet serving as a barely veiled representation of Jews. Towards the end of the episode, however, there is a pretty controversial stance taken towards Nazism--it arrives in the justification for breaking the Prime Directive. Scripter John Meredyth Lucas and Roddenberry are clever enough to wrap their controversial point in an undermined character who is potentially interpretable as a villain for his decisions.
But the reason this episode is so good and unusual isn't because it has profound things to say about Nazism. It's because it does a lot of typical Star Trek things--like Kirk and Spock being held captive, having to bluff their way out of jams, and so on--in a very unusual, very serious way. We usually have little worry that Kirk and Spock will be shortly out of a locked cell, but here, director Vincent McEveety films a very familiar scene so that it is very suspenseful. Likewise, Spock in incongruous disguises or modes often causes laughter, and frequently the threat of him being revealed when he needs to be disguised is just as promising of humor as tension. Here, there's nothing funny about it, it's instead nail-biting. With laudable help from the make-up department, McEveety also manages to truly make Spock feel alien. Even Shatner gives a serious, intense performance rather than hamming it up this time around, and the same goes for DeForest Kelley. In fact, McEveety so successfully achieves a weighty mood that even the typical, somewhat comical bickering between Spock and McCoy takes on an edge of nastiness in the final scene.
I love Star Trek's normal campiness and cheesiness, but Patterns of Force goes to show that it's just as excellent when they try to keep everything on the straight and narrow.
