Stardate: 5928.5
Original airdate: 6/3/1969
Writer: Arthur Singer
Director: Herb Wallerstein

Guest Stars:

Sandra Smith            Dr. Janice Lester, scientist who once was in love with Kirk.
Harry Landers           Dr. Coleman, scientist who loves Dr. Lester.

Story:
Kirk finds himself the victim of Dr. Janice Lester's hatred. She was once romantically involved with the captain, and has been unable to assume a command of her own. Now she wants revenge and has found it in an alien device which is able to transfer her mind to Kirk's body and vice-versa.

Crew Appearances:
Kirk, Spock, McCoy
Scott
Nurse Chapel
Sulu
Chekov
No Uhura
Lt.------- Communications
Two guards, no names given

Factoids:
Selebium: radiation source that poisoned and killed all Lester's staff upon her order

Camus II: planet of ancient civilization that achieved total life entity transference via a mechanical device.

Benicea Colony: 48 hours away, having medical facilities

Beta Aurigae: Destination of the Enterprise during this crisis

Star Base 2: on a direct route to Beta Aurigae, the best place for Lester's diagnosis and treatment.

Uss Potemkin: Enterprise rendezvous with them is being delayed by this crisis.

Rhobdniana dermal optic test: medical test used to detect psychological changes. and determines identity

mentions the Tholians (Tholian Web) and the Vians of Minara(Empath)

Vulcan Mind Touch: Telepathic touch that Spock uses to enter Lesters mind, and finds Kirk, instead.

Quotes:
"I loved you. we could have roamed among the stars." Lester.
"We'd a killed each other." Kirk.

---
"you are insane, Dr. Lester." Colman to Kirk as Lester.

---
"yes, to obtain the power she craved." Kirk in Lester's body.

(confusing enough for you?)

Thus ends the 3 year running of the the greatest science fiction TV show that was ever made. It wasn't a perfect series. Many episodes had their weak points, but the influence of Star Trek in my life cannot be denied.