The Gamesters of Triskelion

Warning: In this episode there is what is implied to be an attempted rape scene

TOS Season 2 Episode 16
Air Date: January 5th, 1968

Kirk, Chekov and Uhura are whisked away to a planet far from the Enterprise by the providers and taken captive to be trained as thralls. The thralls all wear shock collars used to force obedience. After being fed they are taken for training where Uhura is asked to whip a man. She refuses and Kirk ends up taking his place. But Kirk is able to turn the tables and disable the person who was tasked to whip him. This makes him valuable to the providers and they immediately get bid on and assigned to the provider with the color red (the color of their collar).

Meanwhile on the Enterprise, Spock was able to follow an ion trail twelve light years to a location he believes is where the away team was taken. When the Enterprise arrives the providers disable the ship to prevent them from saving the away team. Kirk uses this opportunity to bait the providers into showing themselves. Kirk is transported a thousand meters underground where three brains are housed in a glass chamber.

These brains are the result of an ancient species evolution to not require a body. They need thralls since the only challenge they have left is to create gladiatorial games that they can bet on. Kirk tells the brains that they are too smart to enslave and kill people. He realizes that gambling is the key to what these brains want, so he bets the brains that he can beat the three thralls in combat.

Kirk fights but there is a rule that any injuries to the thralls will have them replaced. He defeats two thralls but after injuring the third, Shahna is chosen to fight. Shahna was a thrall that Kirk was falling in love with. He wins, but doesn't kill her, but the providers still accept the victory.

Part of the conditions of victory was that the thralls would be set free and taught to create a civilization instead of to fight each other.

"It is a nice name: Chee-koof." - Tamoon

"Oh, we, too, have mates. When it is time to increase the herd, my provider will select one for me." - Shahna

"Well, Mr. Spock, if you're going into the lion's den, you'll need a medical officer." - McCoy
"Daniel, as I recall, had only his faith, but I welcome your company, Doctor." - Spock