Spock, Kirk, and McCoy return to the planet of the Guardian of Forever. Ostensibly to assist Federation historians with an investigation into the organization’s past.
| Air Date | 15 September 1973 |
| Production Number | 22003 |
| Stardate | 5363.4 |
| Gregorian Calendar Date | Wednesday, 08 May 2267 09:36:15 GMT & 2236 |
| Primary Arc | The Guardian of Forever |
| Secondary Arc | Temporal Investigations |
| Tertiary Arc | The Vulcan Way |
| See It or Skip It | See It! |
| Previously on Star Trek | Order | Next Time on Star Trek |
|---|---|---|
| One of Our Planets is Missing | Chronological | More Tribbles, More Troubles |
| Beyond the Farthest Star | Air Date | One of Our Planets is Missing |
| The Infinite Vulcan | Production | Beyond the Farthest Star |
| City on the Edge of Forever | Primary Arc | n/a |
| Assignment: Earth | Secondary Arc | All Our Yesterdays |
| The Enterprise Incident | Tertiary Arc | Is There in Truth No Beauty? |
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