The ham-acting at the end is a pretty good quote by Shatner.
PLOT
Captain Tracy (who somehow became an officer in Star Fleet) defies Star
Fleet Command because he thinks he's found a planet of eternal youth, and
decides to meddle in the struggle between the Yangs and the Coms. This
alternate Earth has the U.S. flag, some American documents, and a book
with a picture of Satan who looks like Spock. Kirk and Spock are in a cell
and try to befriend a larger inmate.
FACTS
Alternate Earth.
Captain Tracy is this week's dork.
Defy Star Fleet Command.
Spock sort of uses the Vulcan mind meld across a crowded room.
OPINIONS
Shatner's ham-acting is the only real reason to watch this episode. The
basic plot isn't all that bad, but the execution of it isn't carried off
all that well.