When Kirk discovers that a stage actor named Anton Karidian (Arnold Moss) may really be the believed-dead "Kodos the Executioner," known for executing 4,000 innocent people in the midst of a social crisis, the captain launches a search for the truth. In hopes of learning more, he manipulates Karidian's daughter Lenore (Barbara Anderson) into coming aboard the Enterprise, and finds himself beginning to fall for her.
"The Conscience of the King" is like a stage play brought onto a starship, featuring the classic elements of a Shakespearean tragedy rolled into an episode of Trek. The storyline is accomplished through an ingenious device that is wondrous in the way it threatens to bring down the "fourth wall" separating audience and television production, forcing us to consider the connections between classic literature and now-classic popular culture. It's very creative in its use of archetypes, and Moss and Anderson throw themselves into their roles with the exuberance of, well, stage actors.
Unfortunately, this otherwise stellar episode is almost completely undermined by its inappropriate ending, in which a single line of dialog uttered by McCoy obliterates the tragic realization that played out just moments before. Are we supposed to believe that a woman who has murdered seven people will be set free just because she has suffered a great deal? And that she can be released from her tragic burden through some vague but apparent memory alteration? What kind of authority does Kirk have? And how in the world can you have a tragedy that tries to lighten the mood with a cheat ending?