Gene L. Coon wrote the story under his pen name of "Lee Cronin." It was his last writing contribution to the original series.

McCoy: I've never worked on anyone or anything like him.
Spock: Yet, you are pumping him full of your noxious potions as if he were a human.
McCoy: When in doubt, the book prevails, Mr. Spock!

Kirk: Don't you usually know whose property you've stolen?
Lokai: I am not a thief!
Kirk: Well, certainly no ordinary thief, considering what it is you... appropriated.
Lokai: You're being very loose with your accusations and drawing conclusions without any facts.
Kirk: I do know you made off with a ship that didn't belong to you.
Lokai: I do not make off with things. My need gave me the right to use the ship. Mark the word, sir-- the use of it!
Kirk: You can try those technical evasions on Starfleet Command. That's where you'll be facing your charges.

Lokai: You monotone humans are all alike. First you condemn and then attack!

Bele: You bear precious cargo-- Lokai. He has taken refuge aboard this ship. I am here to claim him.
Kirk: All personnel aboard this vessel are subject to my command. No one claims anyone without due process.
Bele: My apologies, Captain. I overstepped my powers. "Claim" is undoubtedly an unfortunate word.

Lokai: He raided our homes, tore us from our families, herded us together like cattle and then sold us as slaves!
Bele: They were savages, Captain. We took them into our hearts, our homes. We educated them.
Lokai: Yes! Just education enough to serve the master race.
Bele: You were the product of our love! And you repaid us with murder.
Lokai: Why should a slave show mercy to the enslaver?
Bele: Slaves? That was changed thousands of years ago. You were freed.
Lokai: Freed? Were we free to be men? Free to be husbands and fathers? Free to live our lives in equality and dignity?
Bele: Yes, if you knew how to use your freedom. You were free enough to burn all the things that had been built!
Lokai: I tried to break the chains of 100 million people. My only crime is that I failed, to that I do plead guilty.
Bele: There is an order in things. He asks for utopia in a day. It can't be done.
Lokai: Not in a day. And not in ten times 10,000 years by your thinking. To you, we are a breed who will never be ready. Genocide for my people is the plan for your utopia.
Bele: You're insane, you filthy little plotter of ruin! You vicious subverter of every decent thought! Oh, you're coming back to pay for your crimes!
Lokai: I know you and all those with whom you're plotting to take power permanently. When I return to Cheron, you will understand what power is. I will have armies of followers.
Kirk: It's now very clear you know each other extremely well, gentlemen.

Kirk: I have ordered guest quarters for you on deck six. And I suggest you get a great deal of rest. (to Lokai) Especially your vocal chords. It seems you'll have a double opportunity to practice your oratory on Star Base 4.

Lokai: I will not return to Cheron! Captain, you must guarantee me sanctuary.
Bele: He cannot help you now. You are lost, Lokai. You're on the way to judgment, to final punishment.
Lokai: Stop him!
Bele: Not this time, you evil mound of filth. Not this time.
Lokai: My cause is just. All of you must help me!
Bele: Oh, the old cry: Pity me! Pity me! Everywhere he's gone, he's been helped to escape. On every planet he's found fools who bleed for him and shed tears for the oppressed one. But there is no escape for you on this ship. This is your last sanctuary.

Kirk: Twenty-five seconds--let's see you prevent the computer from fulfilling my commands.
Computer: Twenty seconds.
Kirk: From five to zero, no command in the universe can prevent the computer from fulfilling its destruct orders.
Computer: Fifteen seconds.
Kirk: You can use your will to drag this ship to Cheron. But I command the computer. Mine is the final command.

Kirk: Let me reaffirm my position, gentlemen. I could put you in the brig for what you have done, but I won't do it because you are new to this part of the galaxy, which is governed by the United Federation of Planets. We live in peace with full exercise of individual rights. The need to resort to violence and force has long since passed, and it will not be tolerated aboard this ship. You are free to move about the ship. I hope that you'll take the opportunity to know more about the Federation through its best representatives, my crew. But let me make it clear. I will stand for no interference with the function of this ship.

Spock: Fascinating. Two irrevocably hostile humanoids.
Scotty: Disgusting is what I call them.
Spock: That description is not scientifically accurate.
Scotty: Mr. Spock, the word disgusting describes exactly what I feel about those two.
Kirk: That's enough for today. Those two are beginning to affect you.

Lokai: And I know from my actions you must all think me a volcanic hothead, erupting lava from my nostrils at danger signals that are only figments of my imagination. But believe me, my friends, there can be no moment when I can have my guard down where such as Bele is present. So what happens? I act the madman out of the anger and frustration he forces upon me, and there by prove his point that l am a madman.

Chekov: There was persecution on Earth once. I remember reading about it in my history class.
Sulu: Yes, but it happened way back in the 20th century. There's no such primitive thinking today.
Lokai: You have read about it in history, I see. How can I make your flesh know how it feels to see all those who are like you, and only because they are like you, despised, slaughtered, and even worse, denied the simplest bit of decency that is a living being's right? Do you know what it would be like to be dragged out of your hovel into a war on another planet? A battle that will serve your oppressor and bring death to you and your brothers.

Spock: There is the matter of the shuttlecraft which Lokai appropriated. The interrogation of that matter may be of paramount importance to Starfleet.
Bele: Gentlemen, we are discussing a question of degree. Surely, stealing a shuttlecraft cannot be equated with the importance of murdering thousands of people.
Spock: We do not know that Lokai has done that.
Bele: One thing we are agreed on is that Lokai is a criminal.
Kirk: No, Commissioner. The one thing we're agreed upon is that Lokai took a shuttlecraft.

Bele: It is obvious to the most simpleminded that Lokai is of an inferior breed.
Spock: The obvious visual evidence, Commissioner, is that he is of the same breed as yourself.
Bele: Are you blind, Commander Spock? Well, look at me. Look at me!
Kirk: You're black on one side and white on the other.
Bele: I am black on the right side.
Kirk: I fail to see the significant difference.
Bele: Lokai is white on the right side. All of his people are white on the right side.

Spock: Commissioner, perhaps the experience of my own planet Vulcan may set an example of some value to you. Vulcan was in danger of being destroyed by the same conditions and characteristics which threaten to destroy Cheron. We were once a people like yourselves--wildly emotional, often committed to irrationally opposing points of view, leading, of course, to death and destruction. Only the discipline of logic saved my planet from extinction.
Bele: Commander Spock, I am delighted that Vulcan was saved. But you cannot expect Lokai and people like him to act with self-discipline any more than you can expect a planet to stop orbiting its sun.

Lokai: So this is justice after Ariannus! You have signed my death warrant. I warned you what to expect. Will you continue to let this mockery of justice go on? If you are partisans of justice, prove it! Kill him!
Chekov: We are not killers.
Lokai: What do you do, carry justice on your tongues? You will beg for it, but you won't fight or die for it.
Kirk: After so many years of leading the fight, you seem very much alive.
Spock: I doubt that the same can be said for many of his followers.

Uhura: It doesn't make any sense.
Spock: To expect sense from two mentalities of such extreme viewpoints is not logical.
Sulu: But their planet's dead. Does it matter now which one's right?
Spock: Not to Lokai and Bele. All that matters to them is their hate.
Uhura: Do you suppose that's all they ever had?
Kirk: No. But that's all they have left.

in the scene where Lokai addresses the gathered crew, Sulu and Chekov both have (dubbed) dialogue, but Chekov is not in the room.

As Lokai runs toward the transporter room in the last few minutes of the episode, you can briefly glimpse the rope he is holding in his left hand to maintain the proper distance to the mounted camera.

As Bele's ship approaches on a collision course and Sulu says "Brace yourselves!", the camera cuts to a shot from the turbo-lift and Hadley is at Chekov's position.

After the Enterprise leaves Ariannus, Kirk says the stardate is 5370.7. However, after the next commercial break as Bele burns out the controls, Kirk says the stardate is 5370.6.

What Changed in the Remastered Version
General improvements cited on the main series page. The orbital shots of both Ariannus and Cheron get a surface upgrade. Ariannus has a more Earth-like appearance while Cheron has a great deal of reddish surface damage clearly visible from orbit. The "heat" animation surrounding the Cheronites is improved. No decontamination F/X is added to the upgraded scenes of the Enterprise in orbit above Ariannus, however.