Spock being near-death from choriocytosis brings the Enterprise into conflict with Orion pirates when they steal the medication.
This episode includes examples of the following tropes:
- Asteroid Thicket: The title opponents' ship flees into an asteroid field that consists of a large collection of rocks close together. There are so many asteroids that it's easy for the Orion ship to hide among them. What's more, the asteroids consist of a material that explodes upon contact with another asteroid or a ship.
- Cyanide Pill: The Orion captain tries to commit suicide, but two redshirts grab him and prevent it.
- He Knows Too Much: The Orions know they're caught, and the captain plans to blow his own ship and the Enterprise to pieces to protect the Orion image of "neutrality."
- It Is Pronounced "Tro-PAY": "Orion" is pronounced "OH-ree-on".
- Trap Is the Only Option: Hints of this. McCoy and Scotty are suspicious when the Orion captain asks Kirk to beam down to an asteroid to get the medicine he and his crew stole. Kirk agrees that it's dangerous, but he also knows that "without it, Spock doesn't have a chance."
- You Won't Feel a Thing:McCoy: [about to give an injection] This won't hurt a bit, Spock.
Spock: An unnecessary assurance, doctor, in addition to being untrue.
McCoy: That's the last time I waste my bedside manner on a Vulcan.