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?
had a severe case of flu during filming of this episode. At one point he had to lift Sandra Smith
in his arms, carry her to a couch and put her on it: during the first take he got as far as the couch and dropped her. Fortunately it was well padded, and Smith bounced several times; according to Joanie Winston
, who was visiting the set, Shatner looked down at Smith and said, "You know I love you, baby, but you've got to lose about six inches off that ass." See more
When Spock and McCoy are conversing in sickbay, McCoy is wearing his medical garb. However, in the first couple of close-ups, his shirt changes to his regular uniform. See more
Knowledge of the captain's aberrant behavior is spreading through the ship. The crew is becoming increasingly tense.