*** (3 stars out of 5)
No, I'm afraid you're thinking of 'The Terrapin Incident'- where that tortoise beat that hare that time.
"The Terratin Incident" is where the Enterprise crew became shrinky-dinks.
Responding to a coded signal where only the unknown word 'terratin' could be discerned, the ship was bombarded by x-waves above the only satellite of the star Cepheus.
McCoy and Chapel report their extremely fragile gossamer mice are fine, which is a big relief to everyone until Scotty reports the dilithium is ruined and Mess Officer Briel reports the whole ship is getting rapidly bigger. Eek!
Or, as Spock points out, the crew could be shrinking, since their uniforms of algae-based xenylon still fit. In 32 minutes they will be too small to push buttons and adjust dials, which they have heretofore been very fond of doing.
Sulu breaks his leg falling off the console, and his rescuers are nearly too small to activate the door's electric eye. While Chapel is fetching the smallest bone-knitting laser for him, she falls into the halo fish aquarium. Kirk rescues her with a sewing needle and thread.
Needle and thread? I guess it's lucky McCoy's got a lot of antiques?
Two-Inch Kirk with Kung-Fu Grip beams down for answers. (It takes three stout men to work the controls.) When the Captain is rematerialized, he's automatically normal sized! Problem SOLVED.
However, when he returns from the erupting world, his whole tiny crew has been kidnapped by the transporters of the surface people! Wait, wait, WHAT? You JUST showed us how the transporter resets size, remember?
The ruling Mendant of the colony Terra Ten, (corrupted to Terratin by a group that retained teleportation technology but apparently not WRITING WORDS DOWN??), is a sixteenth of an inch high because of the natually occurring spiroid epsilon waves. The trait is now a genetic characteristic in these colonists. Simple. (But still doesn't explain why their transporters didn't instantly restore the crew...)
Apparently out of pride, the Terratins never asked for help before (or used their transporters even once in the last two centuries?), but are now under threat from volcanic eruptions.
I don't understand their plan. Their ONLY way to reach Enterprise was to shrink them? What about talking to them on the communicator, as they are doing RIGHT NOW? For that matter, why did they call for help in code in the first place? Next time I'm the size of a water-bug and the magma is rolling my way, I don't think I'll sit down and devise puzzles.
Because they are very forgiving people, our heroes beam up the entire city (it's the size of a single transporter pad) for relocation to planet Verdanis.
I have to imagine the script got shrunk, too. The idea of a rapidly diminishing crew is really very cool, with everyday objects becoming menacing obstacles, but the resolution is too easy and magically inconsistent transporters save the day again.