Star Trek's original run started with The Edge of the Galaxy and this show, which represents what a 4th season would have looked like, closes that circle- Even starts a new circle, as it points toward the Motion Picture of 1979.
A small mystery had erupted in a few of the earlier episodes from this "season" - Starfleet's 12 Constitution Class Ships are being destroyed, one by one.
That gets dealt with in this two part finale.
Kirk and crew are called to a colony of people with high Esper ratings. And there is a "Romulan" there. All of the colonists are missing, with one one left who appears who have been "escalated", but professing fealty to Starfleet.
It's a deception. To get to the Bottom of it, Spock calls on his old girlfriend, the Romulan Commander from "The Enterprise Incident", played here by Amy Rydell (Who happens to be the daughter of the original actress, Joanne Linville), to help them track down a missing frigate that the remaining Espers might have stolen.
There is only one place they could have gone - To the edge of the Galaxy.
To get there fast, the Enterprise and Romulan Warbird join engines.
But when they get there...
