S4E1 "She who must be obeyed".
The Enterprise is on routine patrol, when Ohura picks up a weak subspace signal. Spock triangulates and declares such a signal must be impossible since it comes from a colony set up and believed lost 300 years ago.
The Enterprise goes into orbit and Kirk, Spock and McCoy beam down with Ohura whose relatives were part of the original colonists.
Chariots driven only by beautiful young women arrive. Kirk draws his phaser but the lead female disables it with her whip.
They are bound and led to the city, except Ohura, who rides with the girls.
The men are tried on abducting a female with the lead, Jakinda [Jane Fonda], judging. As they are being marched to the labour camps, she is impressed by Kirk and Spock and they may be "breeding material".
Caged, it is now made obvious they must fight to the death for the right to breed with the females who rule the planet.
On couches, Ohuru, now dressed in the same outfit as Jakinda and the other girls await the fighters, while being served by docile men.
Kirk watches the first fight which the girls enjoy highly. He offers a truce to his opponent, but "this is not the way".
Jacinda takes victorious Kirk to her boudiour. Kirk refuses and states that men and women are supposed to be equal partners.
Ohuru points out to Bones that there is something peculiar about the fruit he is serving her. McCoy realises it is upsetting the natural hormones and vows to find an antidode.
After irking Jakinda he now has to fight his friend Spock, who at first is stronger, but dies with a spear to the chest.
Jakinda now taunts Kirk with her lovely body. Kirk takes control. They are finished and now you see love in her eyes.
She explains she has never felt like this before. Bones and Uhura arrive and he explains he has put the antidote in the water supply.
Jakinda agrees to revoke male discrimination and return the colony to normal, as Spock turns up.
"It's good you remembered a Vulcan's heart is on the right hand side, Captain."
"Oh, I didnt know Mr Spock: everybody gets lucky sometime."