*** (3 stars out of 5)
It looks like the folks at Elba II missed a couple of homicidal nuts when they found the last 15 in the galaxy back in "Whom Gods Destroy".
Dr. Janice Lester, space archeologist, and Dr. Coleman, MD (Malpractice Douchebag) found an ancient alien mind-switching machine on Camus II. She ordered their team of witnesses into areas of deadly radiation and he failed to treat them. Then they hatched a dastardly scheme. Fiendish, even.
Bones has "Kirk" submit to exams including the Robbiani dermal-optic test to reveal basic emotional structure. Spock talks logic with "Lester" who acts very much like Jim, and telepathically reads as Jim. Telepathy is not admissable, and the Robbiani doesn't show an emotional disorder. (Some test! What happened to the brain scan that conclusively showed Mira Romaine was possessed? Not to mention the psychotricorder...)
Coleman's attempted murder of Prisoner Girl Kirk prompts their minds to switch back. Coleman says he'll look after Janice, but I hope no one lets him. You know... murderers.
Kirk's final line "Her life could have been as rich as any woman's. If only... if only.." Well, it's very Enigmatic, kids.
If only... Starfleet gave Captain's seats to homicidal maniacs?
If only... Kirk hadn't shattered Lester's mind when he left her for some blonde?
If only... women knew their limits?
If only... she was guest starring on 'The Mod Squad' instead?
"Turnabout Intruder" works on a pair of strong gender-swapped performances. It's no 'Freaky Friday' or the one with Ryan Reynolds and Jason Bateman urinating, but it's O.K.
Season 3 is weak, but without it Star Trek would not have reached syndication.
Where it got noticed big time.
And its legend grew.