Data Stellare sconosciuta: L'Enterprise è in orbita attorno ad Halka per trattare con gli abitanti locali l'avvio di relazioni diplomatiche per l'ingresso nella Federazione. Ma un guasto al teletrasporto causato da una tempesta ionica materializza Kirk, McCoy, Scott e Uhura nell'Universo dello Specchio.

Kirk: Conquest is easy. Control is not.

Kirk: If change is inevitable, predictable, beneficial... doesn't logic demand that you be a part of it?
Spock dello Specchio: One man cannot summon the future.
Kirk: But one man can change the present.

Kirk: In every revolution, there's one man with a vision.

McCoy: I'm a doctor, not an engineer.
Scott: Now you're an engineer.

McCoy: You're a man of integrity in both universes, Mister Spock.

Spock: They were brutal, savage, unprincipled, uncivilized, treacherous. In every way, splendid examples of homo sapiens, the very flower of humanity. I found them quite refreshing.