The City on the Edge of Forever

"The City on the Edge of Forever" is the twenty-eighth and penultimate episode of the first season of the American science fiction television series Star Trek. It was written by Harlan Ellison; contributors to and/or editors of the script included Steven W. Carabatsos, D. C. Fontana and Gene L. Coon. Gene Roddenberry made the final re-write. The episode was directed by Joseph Pevney and first aired on NBC on April 6, 1967.

In the episode, Doctor Leonard McCoy (DeForest Kelley) accidentally overdoses himself with a dangerous drug. He transports himself down to a mysterious planet while not in his right mind and is pursued by a rescue party led by Captain Kirk (William Shatner) and Spock (Leonard Nimoy), who soon come across the Guardian of Forever, a sentient time portal. McCoy travels back in time while impaired and changes history to such an extent that the Federation of Planets no longer exists. Kirk and Spock follow him to Depression-era New York City to attempt to fix the damage. While in the past, Kirk falls in love with Edith Keeler (Joan Collins), a soup kitchen operator who dreams of a future much like his own 23rd Century. Spock eventually discovers that McCoy had changed the course of history by saving Keeler from dying in a traffic collision. Much to his personal grief, Kirk allows the crash to take place, restoring history.

The episode received widespread critical acclaim and is frequently considered among the best episodes of the Star Trek franchise. Elements such as the tragic ending were highlighted by several reviewers. It won several awards, including the Writers Guild of America Award for Best Episodic Drama on Television (Ellison, 1967) and the Hugo Award for Best Dramatic Presentation (Ellison and Pevney, 1968).