Arena
Set on revenge for a massacre on a Federation outpost, Kirk pursues the ship of the lizard-like Gorn race into an unexplored area of the galaxy and finds himself in a one-on-one fight with the Gorn captain.
The first 15 minutes of this episode are definitely the most intense and exciting, with the enemy still invisible and our heroes dodging real blasts. (Proof the show's producers were nuts: the most basic fight warranted a bad stunt double, yet the actors were sent running through mine fields!) Kirk wandering round the asteroid is less thrilling, though Gorn might be the best alien yet. The captain learns revenge isn't the answer and renews his respect for other life forms. Removed from the convenience of his ship's tools and weapons, he can't bring himself to kill with his bare hands. Having the bridge crew serve as spectators and narrators is preferable to the "find the missing officers in 100 parsecs of space" subplot. The Metrons are among the more plausible super beings, though kind of fruity. Yet this episode is more about Kirk finding his sense of mercy than the Metrons finding this sense in humans. And if this lesson involves explosions, fights, and giant lizards, no complaining.
Spock Saves the Day: Spock's continued pleas for mercy likely influenced Jim's final decision not to kill the Gorn captain.
Oops: Spock is error-free today.
Developments: Spock's deep respect for other life forms - even those seemingly hostile - is emphasized once again. As in The Galileo Seven and soon in The Devil in the Dark he believes in showing mercy even if it brings him into opposition with the hard-line Kirk. We can only wonder what the Metrons would tell him, apart from " Keep it up!"