Ep 9. Metamorphosis

Captain Kirk, Mr. Spock, and Dr. McCoy are on a mission to transport Federation Commissioner Nancy Hedford to a flagship medical facility for treatment of an unknown illness. However, their journey takes an unexpected turn when their shuttlecraft is drawn into an energy field and crash lands on a distant planet.

As they explore their surroundings, they come across a mysterious man named Zefram Cochrane, who was believed to have died centuries ago. It turns out that Cochrane has been living on the planet for years alongside a being known as the Companion, who keeps him alive and youthful.

The Companion reveals that it has brought the trio to the planet specifically to help Cochrane, who has grown lonely and wishes to leave the planet. In order to do so, however, the Companion will have to merge with a human being and transform into a physical form capable of leaving the planet.

Commissioner Hedford sees an opportunity and volunteers for the transformation, hoping to regain her health in the process. But as the transformation takes place, she and Cochrane form an unexpected connection, forcing Kirk, Spock, and McCoy to intervene in order to save them all.

With themes of love, sacrifice, and the nature of existence, "Metamorphosis" is a memorable episode of "Star Trek" that explores the depths of what it means to be human, or in this case, an alien being seeking a sense of belonging and purpose.