A Quick Tip by fatherz

"The City on the Edge of Forever" is the penultimate episode of the first season of the television series Star Trek. It is episode #28, production #28, first broadcast on April 6, 1967. It was repeated on August 31, 1967 and marked the last time that NBC telecast an episode of the series on Thursday nights. It was one of the most critically acclaimed episodes of the series and was awarded the 1968 Hugo Award for Best Dramatic Presentation. The only other episode with such an honor is the two-part episode "The Menagerie". The teleplay is credited to Harlan Ellison, but was also largely rewritten by several authors before filming. The filming was directed by Joseph Pevney. Joan Collins guest starred as Edith Keeler.

This episode involves the crew of the starship USS Enterprise discovering a portal through space and time, which leads to Dr. McCoy's accidentally altering history.