2. Bem

Stardate: 7403.6 The Enterprise crew is joined by a unpredictable alien called Ari bn Bem, an independent observer from the planet Pandro.

3. The Practical Joker

Stardate: 3183.3 The computer of the Enterprise gains partial sentience and starts playing practical jokes on the crew.

4. Albatross

Stardate: 5275.6 Dr. McCoy is arrested and held responsible for causing a plague that ravaged the planet Dramia II, where he performed a mass-innoculation 19 years earlier.

5. How Sharper Than a Serpent's Tooth

Stardate: 6063.4 The Enterprise runs into a being that once visited Earth and influenced the Mayan culture.

6. The Counter-Clock Incident

Stardate: 6770.3 With Commodore Robert April (the first commander of the Enterprise) on board, Kirk pursues a ship plunging into a supernova, and enters a universe where time runs backwards.