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 US during the Great Depression, where they have no advanced technology available. Written by
Did You Know?
Originally then-story editor Steven W. Carabatsos
got the job to rewrite Harlan Ellison
's script, but his draft was not used. Instead, Ellison agreed to make a rewrite himself, which was again deemed unsuitable. Producer Gene L. Coon
also got himself into the rewriting. Finally, the new story editor, D.C. Fontana
got the assignment to rewrite Ellison's script and make it suitable for the series. Fontana's draft was then slightly rewritten by Roddenberry to become the final shooting draft. Much of the finished episode is the product of Fontana, who went uncredited (as did all the other writers) for her contribution. Only two lines from Ellison's original teleplay survive in the final episode, both spoken by the Guardian: "Since before your sun burned hot in space, since before your race was born," and "Time has resumed its shape." See more
When McCoy first runs into the area of the portal and away from the landing party, he puts his hand on a brown metal or concrete beam lying flat on the ground (in ruins). However, the beam can be seen moving back and forth with his light touch-obviously a prop. See more
Assassins! Murderers! Murderers! Assassins!
[spots a homeless man
You! What planet is this?
[the man runs away
[chasing after him, shouting crazily
No! Don't run! I won't kill you! It's THEY who do the killing! Don't run! I won't kill you!
Script Supervisor is written as "SCPIPT SUPERVISOR...GEORGE A. RUTTER" in the credits. This happened on at least two other episodes in season one. See more