Kirk, Spock, and McCoy are accidentally shoved through a time portal while strolling through a library on the planet Sarpeidon, whose star, Beta Niobe is about to go supernova.
| Air Date | 14 March 1969 |
| Production Number | 60043-78 |
| Stardate | 5943.7 |
| Gregorian Calendar Date | Friday, 15 May 2268 16:10:12 GMT Friday, 15 May 2268 19:39:47 GMT |
| Primary Arc | Temporal Investigations |
| Secondary Arc | The Vulcan Way |
| Tertiary Arc | Beta Niobe |
| See It or Skip It | See It! |
| Previously on Star Trek | Order | Next Time on Star Trek |
|---|---|---|
| Turnabout Intruder | Chronological | How Sharper Than a Serpent’s Tooth |
| The Savage Curtain | Air Date | Turnabout Intruder |
| The Savage Curtain | Production | Turnabout Intruder |
| Yesteryear | Primary Arc | The Voyage Home |
| Is There in Truth No Beauty? | Secondary Arc | The Motion Picture |
| n/a | Tertiary Arc | The Counter-Clock Incident |
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