On an urgent medical emergency, Kirk, Spock and McCoy encounter an alien society that had once flourished on earth during the time of Plato. Since reaching their current planet, they've developed psychokinetic powers while also losing their bodies' ability to combat even the simplest infection, making the need for a physician newly apparent. When Dr. McCoy declines their invitation to stay, they begin to make sport with Kirk, Spock, Nurse Chapel and Lieutenant Uhura using their psychokinetic powers.
Did You Know?
There is some dispute about whether the kiss actually occurred. According to the on-screen footage, it appears that the actors' lips touched. However, both William Shatner and Nichelle Nichols claimed in Star Trek Memories that NBC exerted pressure to forbid lip contact, and to use a clever camera technique to conceal the "separation". If you look closely, you can tell that the actors' lips are not touching; the angle only makes it look like they might be slightly touching. See more
Spock's ears are quite obviously fake prosthetic ears when he and Kirk wear the laurel wreaths on their heads towards the end of this episode. His left ear in particular has been bent to prevent the wreath slipping down any further and because of this it looks very abnormal and fake. See more
Alexander, you talk too much.
Featured in The True Story: Star Trek