#11: The Immunity Syndrome
In case you forgot: This week, it's the Enterprise versus a giant, energy-sucking space amoeba. Spock barely survives the ordeal.
Sometimes it's hard to highlight exactly what it is that makes an episode good. It's like a Monet painting: you can't see anything of the painting in an individual speck, you have to step back and evaluate it as a whole. "The Immunity Syndrome" is one of those episodes. The pace is solid, the threat is very real and very ominous, the monster is actually somewhat plausible, and none of the danger is a result of anyone holding the idiot ball. Spock, in particular, gets to have his stoic moment of bravery by taking the shuttlecraft on a near-suicide mission. Those are all the little pointillist-style dots of the episode, when really all that need be said about it is: it's a top-rate space adventure.
A little bit of weird retconning: Vulcans don't know defeat because they've never been conquered? But what do you call the guy who loses kal-if-fee?