"Turnabout Intruder" is a third season, as well as the final first-run, episode of Star Trek: The Original Series. It is episode #79, production #79, written by Arthur H. Singer, based on a story by Gene Roddenberry, and directed by Herb Wallerstein. This was the last original episode of Star Trek to air on NBC.
Originally scheduled to air at 10pm on Friday, March 28, 1969, the network pre-empted it at the last minute with a special report on former U.S. President Dwight D. Eisenhower, who had died earlier that day. On June 3, 1969, after an absence of 2 months, Star Trek was brought back on a new night and time: Tuesdays at 7:30pm EDT. "Turnabout Intruder" was the first and only episode to be shown in this new time slot.
Overview: Captain Kirk becomes trapped in the body of a mentally unstable woman bent on killing him and taking over his command in his guise.
Read more about Turnabout Intruder: Plot, 40th Anniversary Remastering, Reception