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?
This was the most expensive episode produced during the first season, with a budget of $245,316, and also the most expensive episode of the entire series, except the two pilots. The average cost of a first season episode was around $190,000. Also, production went one and a half days over schedule, resulting in eight shooting days instead of the usual six. See more
One building front shows a fallout shelter sign, not used until after WWII. See more
Assassins! Murderers! Murderers! Assassins!
[he spots a homeless man
You! What planet is this?
[the homeless 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 George Rutter
is written as "SCPIPT SUPERVISOR...GEORGE A. RUTTER" in the credits. This happened on at least two other episodes in season one. See more
Special Enhanced version Digitally Remastered with new exterior shots and remade opening theme song See more
Theme From Star Trek
Written by Alexander Courage See more