I had assumed the second episode, the Spock-centric “Yesteryear,” was perhaps the best episode of the animated series. But then I saw “One of Our Planets is Missing” and, well, it was also pretty good.
OK, true, the animation is still rather cheap, but the story actually makes up for it considering most of the action is the various characters talking to each other on the bridge. Heck, that three-armed helmsman Arex even gets to talk this time.
To put it bluntly: a giant cloud composed of both matter and energy enters the galaxy. The Enterprise is sent to investigate, and they observe the cloud basically absorb an unpopulated planet. And then the cloud not only changes course to head for a heavily-populated planet that won’t have time to evacuate, but it swallows the Enterprise along the way.
What makes this episode is that the crew basically works together to find a solution. Both Spock and McCoy, coming at the issue from different angles, deduce the cloud is a living thing. It’s an immensely large living thing, but it’s still alive. Scotty at one point has to recharge the engines using anti-matter transported in from the cloud’s digestive system. Kirk acts as the calm center of the storm. And then, when the decision needs to be made to either destroy the cloud by blowing up the Enterprise by its brain or trying to talk to it, it’s Star Trek, so of course they choose to talk.
They talk by having Spock mind-meld through the ship’s censors or something. It’s weird. And then Kirk just shows the cloud images of people. The cloud had no idea there were living things there, and horrified over what it almost did, turns and departs the galaxy. No one dies, and everything worked out because the Enterprise has a crew full of capable, optimistic people who use violence only as a last resort.
And since this story was told over about twenty minutes, I really don’t have anything else to add. It was just a smart episode of an animated series based off a classic sci-fi show.
Even if the characters can barely move.