Harry Mudd is back! I really dig Harry Mudd. Space pirate with the vague Irish brogue, more of a pest than anything else. This time he is caught selling snake oil that actually works. A love potion! And Nurse Chapel uses it on Spock! (I gotta say, Nurse Chapel is a lot sexier in animated form then she is in real life — Spock catches a break here.) Also, the weird Catwoman who sits in for Lt. Uhura (Lt. M’ress, a Caitian, if you must know) falls for Scotty.
But one attempted kidnapping and a battle with some rock monsters later and things wind up back to normal. You can trust that Spock describes his emotional outburst as most illogical.