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.

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.

Stardate: 6334.1 With Spock stricken down by a fatal disease, the Enterprise must track down the drug that can cure him before it is too late.

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

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

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