The Enterprise investigates conditions on planet Argo, currently a water world whose previous dry world history matches events about to befall a nearly identical Federation planet. Kirk and Spock encounter the native sea-dwelling Aquans, who save the pair from drowning by transforming them into water-breathers but otherwise want nothing to do with them. Kirk and Spock seek to reverse their transformations before a devastating earthquake strikes, which requires the capture of a sea monster.
Did You Know?
Since the small boat or "scouter gig" used in the search for Kirk and Spock obviously has no flight capability, it had to have been beamed down. This confirms that "Enterprise" has the cargo transporter shown in Franz Joseph's "Enterprise" blueprints. See more
After Kirk's mutated hands are shown to heal, they are again mutated in a later scene. See more
Captain James T. Kirk
I can't command a ship from inside an aquarium.