In 2019 CBR (Comic Book Resources) rated this season as the second best of all Star Trek seasons up until that time. This placed it just behind Deep Space 9 Season 6. https://www.cbr.com/every-star-trek-tv-season-ranked/. A notable addition to the cast is character of Checkov, the Navigator.

Amok Time (September 15, 1967)

Spock starts to exhibit unusual behavior which bothers McCoy. Then he requests leave on Vulcan immediately. McCoy explains to Kirk that Spock will die in about 8 days if nothing is done, but Starfleet refuses Kirk’s request to divert to Vulcan. Kirk decides that his career is not worth the life of his friend, and goes to Vulcan. There Spock is to undergo a marriage ceremony and invites Kirk and McCoy to be his witnesses/companions. Only it turns out to be more than just a ceremony. Spock is in an insane state, and ends up in a fight to the death with Kirk, but McCoy cleverly gives a Kirk a nerve paralyzer that simulates death. Believing he has killed his friend, Spock snaps out of it, and then discovers the girl didn’t want him anyway.

This story was written by Theodore Sturgeon and is considered one of the best episodes of Star Trek.

Who Mourns For Adonais? (September 22, 1967)

The Enterprise is near a planet when a giant green hand comes up and grabs the ship, and they cannot get loose from it. Then a face appears in the screen, and it it the god Apollo from Greek myths and legends. He takes makes the officers beam down to the planet, and demands that they worship him, but somehow the crew declines to do so. Apparently the Greek gods were not myths, but aliens with certain powers. They left Earth and returned to this planet, and one by one drifted away until only Apollo was left. He is able to channel energy through his body in some way and uses that to zap anyone who tries to oppose his wishes. Eventually they trace the source of the power to the Greek Temple structure, and are able to blow it up, after which Apollo leaves to join the other gods. The title translates as “who mourns for gods” and is taken from a poem by Shelley lamenting the death of Keats. It is an average story, and has similarities to The Squire of Gothos from the first season.

The Changeling (September 29, 1967)

The Enterprise is attacked by something that calls itself Nomad, which turns out to be a space probe from way back in the 20th century. It was presumed destroyed when it hit a meteor, but it encountered another probe from another race and they merged together. This new entity has a mission to destroy all “imperfect life”, which pretty much means everyone . It mistakes Kirk for its maker, which gives Kirk some control, but then Kirk admits that he too is an imperfect life form. In the end he is able to convince Nomad that it too is an imperfect life form, causing it to self-destruct. Elements of this plot made it into the first Star Trek movie, as you may have recognized.

Mirror, Mirror (October 6, 1967)

The Apple (October 13, 1967)

The Doomsday Machine (October 20, 1967)

Catspaw (October 27, 1967)

I, Mudd (November 3, 1967)

Metamorphosis (November 10, 1967)

Journey to Babel (November 17, 1967)

Friday’s Child (December 1, 1967)

The Deadly Years (December 8, 1967)

Obsession (December 15, 1967)

Wolf in the Fold (December 22, 1967)

The Trouble with Tribbles (December 29, 1967)

The Gamesters of Triskelion (January 5, 1968)

A Piece of the Action (January 12, 1968)

The Immunity Syndrome (January 19, 1968)

A Private Little War (February 2, 1968)

Return to Tomorrow (February 9, 1968)

Patterns of Force (February 16, 1968)

By Any Other Name (February 23, 1968)

The Omega Glory (March 1, 1968)

The Ultimate Computer (March 8, 1968)

Bread and Circuses (March 15,1968)

Assignment: Earth (March 22, 1968)