Well, gee…this one is just kinda silly, isn’t it? Even by Doctor Who standards of this era?
So, the Doctor tried to reason with the ruler of Atlantis, but he’s too enthralled with the idea of raising Atlantis back above the waves as promised by Professor Zaroff. Zaroff is madder than a hatter, but he has power where the Doctor has none, so the Doctor and his priest friend are taken off to be executed in the temple by a lot of men in silly hats and the occasional fish mask. Can the Doctor and his new buddy survive?
Yeah, actually. Ben pretends to be the god and speaks through the idol’s mouth, telling the priests to not look and allow the Doctor and his buddy to escape to the hidden tunnels behind the idol.
Wait, that worked?
Yeah. The other priests think it was a miracle.
So, the Doctor has at his disposal Ben, Polly, Jamie, two former sailors, that priest, and a slavegirl to help him. He has two ideas. First, he wants to kidnap Zaroff and keep him from trying to raise Atlantis by draining the ocean and blowing up the planet. I suppose “shooting out into the vacuum of space” would count as raising Atlantis. But yeah, that would be bad. What kind of scientist wants that sort of power? The crazy kind apparently.
The other part of the plan is to get the really silly-looking fish people to strike. They need to be constantly bringing food to Atlantis because food doesn’t stay good for very long there. Just having the fish people stop for a little while will bring the city to its knees. They agree without speaking English, but there is a scene of the fish people swimming around underwater that was probably just the actors moving slowly while being held aloft in an underwater set where I could see wires attached to the guy at least once.
Does the Doctor stop the “destroy the world” plan? Oh hell no. This is a four part story, and this is only part three. While the Doctor does take Zaroff prisoner, Zaroff manages to escape, taking Polly as a temporary hostage and stabbing the priest. That priest guy doesn’t die, but the leader of Atlantis does when he decides to stop the experiment when he gets the (very accurate) idea that he’s not in charge anymore, and Zaroff just shoots him and a couple guards.
See? This is very silly. Even by Second Doctor standards.