In answering a medical emergency at an archaeological expedition, Kirk confronts the deep hatred of an old love, Janice Lester, who supposedly lies severely ill from celebium radiation. In payment for jilting her back at Starfleet Academy, Dr. Lester arranges for an alien machine to swap her consciousness with that of the captain and takes command of the Enterprise. Once aboard, Kirk (in Lester's body) tries to convince Spock that he is trapped in her body. As a result, Janice (in Kirk's body) conducts a court-marshal with the intent of executing Spock and Kirk (in Janice's body), and later McCoy and Scott, to keep her secret. The crew realize something is seriously wrong with their captain and, not wishing to incur an illegal death-penalty themselves, begin a passive resistance. Written by
Did You Know?
This is the only time in TOS that Captain Kirk is portrayed by another actor. See more
After Dr. Lester, in Kirk's body, first arrives on the bridge and starts issuing orders, a wide shot of the bridge and viewing screen clearly shows a blond crewman (stock footage featuring Bill Blackburn
) other than Chekov at the navigator station. At the tail end of this shot, Lester/Kirk specifically addresses his order to Chekov. In the very next shot Chekov is suddenly at the navigator station to hear the rest of Lester/Kirk's order. See more
Doctor, I've seen the captain feverish, sick, drunk, delirious, terrified, overjoyed, boiling mad... but up to now, I have never seen him red-faced with hysteria.