Kirk, Scott, McCoy and Uhura accidentally switch places with their malevolent counterparts from a parallel universe.
A boy comes to Dodge City in search of his father, only to learn that the man is a wanted criminal.
Kuryakin stows away aboard a THRUSH ship carrying a tidal-wave device being used to extort $10 billion; guest Dan O'Herlihy.
Doris changes a man's opinion of women.
A resident is praised for killing a wanted man. The truth comes out when a reporter investigates.