Some early science fiction shows on both radio and television would occasionally adapt stories from the “pulp magazines”, where science fiction thrived in those days. Twilight Zone, Dimension X, X Minus One, and Outer Limits all adapted short stories for episodes. Star Trek did the same thing, using the Frederic Brown short story “Arena” for the episode of the same name. (You can listen to an episode of Escape Pod where the original story is read here)
The Enterprise arrives at the Cestus III Outpost only to find it obliterated. Kirk and an away team beam down to investigate and find only one survivor. Two red shirts die when an unknown vessel attacks the station and the Enterprise. Kirk uses a grenade launcher to scatter the enemy before beaming back to the Enterprise to give chase.
Both ships enter an uncharted region before being spotted by the Metron, an omnipotent race. The Metron are isolationist and force both ships’ captains to fight each other to the death on a planet that they claim will have all the resources they will need for the battle.
It is here that we are introduced to the Gorn, the species that destroyed the space station. They are a reptilian species whose intelligence is at least on par with humans. The Gorn captain exhibits both his cunning and inhuman strength during the battle by rigging traps to cause Kirk to drop his guard. He then goads Kirk into facing him head-on, saying he’ll put him out of his misery. Kirk accuses the Gorn of murdering people. The Gorn, however, informs him that the station had invaded his people’s territory and they were only defending themselves. Realizing the possibility of error, Kirk refuses to kill the Gorn. A Metron appears to congratulate Kirk for showing mercy. He offers to destroy the Gorn ship, but Kirk is adamant to spare him, impressing the Metron further.This is one of the most celebrated episodes of the original series. It is meant as a commentary on humanity’s dual natures as civilized and violent.