When an accident causes Dr. McCoy to go temporarily insane, he escapes to a strange planet. There, the search party discovers a device left by a superior, vanished civilization, a time portal that plays the history of Earth for them - but then Bones jumps through it into the past, causing a change in history important enough to make the Enterprise vanish. Kirk and Spock, who fortunately made a tricorder recording, must attempt to go through to just before McCoy's arrival and stop him from changing history in the United States during the Great Depression, where they have no advanced technology available.
Did You Know?
After Kirk and Spock talk about the "flop", the scene changes to a street view, where a kosher meat store, with a conspicuously large Star of David on its front, is displayed in the center of the scene. This is one of the very few times a human (Earth) religious symbol is displayed in this series. See more
About 6 minutes in Uhura uses her communicator and part of it is flipped open much too wide as she talks into it. Later, at about 10 minutes, she uses it again and it is flipped open normally. See more
Spock... I believe... I'm in love with Edith Keeler.
Jim, Edith Keeler must die.
The closing credits are set against a combination background of stills from that episode and previous episodes, as is standard Star Trek: TOS practice. See more
Syndication versions since the early 1980s and most home video prints replace a recording of "Goodnight Sweetheart" heard in this episode with a generic instrumental track due to music rights issues. The original recording was heard in reruns prior to then and on an early 1980's VHS release by Paramount. The original version was restored when the series was released to DVD. See more
Referenced in StarTalk: William Shatner
Theme From Star Trek
Written by Alexander Courage See more