delivers a revolutionary new drug to Elba II, a planet that houses the Federation's last asylum for the remaining 15 individuals who can't be cured of their insanity. Kirk and Spock beam down with the drug to meet with Dr. Donald Cory, Elba's governor. The planet has a poisonous atmosphere and a force field to contain and protect its staff and patients, and Cory reestablishes the force field as soon as Kirk and Spock beam down. Kirk asks about Cory's newest patient: Fleet Captain Garth of Izar. Cory isn't optimistic about Garth's recovery but takes Kirk and Spock to see the fleet captain, one of Kirk's idols. On they way they see another patient, an Orion slave girl named Marta, in her cell. She claims she isn't insane and that Cory is an imposter.
There's nothing the matter with me! Can't you see just by looking at me? Can't you tell by listening?
She sounds rational enough, Captain.
I am rational.
Cory, Kirk, and Spock arrive at Garth's cell… only to find Cory inside, suspended from the ceiling. "Cory" draws a phaser and shape shifts into Garth. Garth releases the other patients, revealing he has taken control of the asylum and now plans to conquer the galaxy. After destroying the medicine, Garth stuns Spock and has his "subjects" take him away, then Kirk convinces him to release Cory from his torture. Garth assumes the form of Kirk and leaves with his consort, Marta, and Cory explains that Garth learned cellular regeneration from the people of Antos, then mastered it to the degree that he could change his appearance.
The people of Antos taught him the techniques of cellular metamorphosis...
to restore the destroyed parts of his body. By himself, he later learned to use the technique... to recreate himself into any form he wished.
Garth-as-Kirk tries to get Scott to beam him up but the real Kirk has taken the precaution of establishing a password to verify he is whom he claims. When he can't provide the countersign, Garth quickly claims that he was testing Scotty and cuts off, then flies into a fury. A suspicious Scotty tries to reestablish contact without success, but they can't penetrate the planetary force field without killing everyone inside of it.
We are going to take the Enterprise, do you hear me? We are going to take her...
if I have to shatter every bone in Captain Kirk's body.
Garth has Kirk and Spock brought to him for dinner and Marta dances and then flirts with Kirk, making Garth jealous. The fleet captain tries to convince the two men to join him in is war of conquest but again goes insanely angry when Spock points out how illogical his goal is. Spock is taken away and Garth tries to get the countersign from Kirk. When the captain refuses, Garth has Cory brought in and tortures him using a modified sonic therapy chair. When Kirk still doesn't break, Garth uses the chair on him until he passes out. Marta convinces Garth to let her try and get Kirk on their side and Garth agrees.
The pain is real and can be prolonged indefinitely, because there is no actual destruction of tissue.
While Scotty and the others try to find a way through the force field, Kirk wakes up to find Marta tending to him. She tries to get on his good side, claiming she arranged for Spock to be secretly released. Kirk tries to get her to drop the force field and help him return to the Enterprise
. She refuses and tries to stab Kirk out of love. He manages to disarm her and an armed Spock arrives to render her unconscious. They make their way to the control room containing the force field switch and stun an inmate so that Kirk can take his phaser. Spock lowers the force field while Kirk contacts the Enterprise
, and the first officer insists that Kirk return to the ship while he take command of the security team upon arrival. Suspicious, Kirk orders Spock to give the countersign. "Spock" refuses and reestablishes the force field, then transforms back into Garth. The fleet captain set up the entire thing, including making sure the inmate's phaser pack was empty. Garth demands that Kirk bow down before him, then stuns the captain when he tries to get to the force field controls.
were the finest student at the Academy, the finest starship captain. You were the prototype, the model for the rest of us.
Yes, I do remember that. It was a great responsibility, but one I was proud to bear.
Garth has Kirk and Spock taken to the main room where he is to be crowned Master of the Universe, with Kirk as his heir apparent. The inmates go through with the ceremony and Garth has Kirk taken to the control room. After Kirk fails to convince the inmates to help him, Garth arrives and displays a new super-explosive that he's created. He then opens a view screen to reveal that he has forced Marta out into the poisonous atmosphere. Garth has placed a small bit of his explosive in her necklace and detonates it, killing her to spare her further suffering. The Enterprise
detects the explosion and Scotty orders the ship to the far side of the planet to try and cut through the force field at its weakest spot.
I've ordered my men to drive her out of the protective dome. And, of course, she would choke to death on the outside in minutes, but I've arranged a more merciful end for her...
because after all, Captain, she is my consort. One tiny crystal implanted in her necklace, a portion of this explosive no bigger than a grain of sand. I propose to detonate it from here.
When Kirk still refuses to provide Garth with the countersign, Garth sends two of his subjects to get Spock. The Vulcan quickly renders them unconscious and arrives at the control room… only to find himself confronting two Kirks. Both of them refuse to give the countersign so the other can't get it (or so each one claims), and that any security team could be walking into a trap. Spock concludes that Garth will soon run out of energy to maintain his shape shifted appearance. One of the Kirks attacks Spock, knocking him to the ground, and the other one fights his counterpart. The two men struggle until one triumphs, and the defeated Kirk tells Spock to stun them both. Convinced, Spock shoots down the winning Kirk, figuring the loser must have been the one Garth tortured. "Kirk" convinces unconscious and reverts to Garth.
You must shoot, but shoot both of us. It's the only way to ensure the safety of the Enterprise.
With the force field down, McCoy and his team beam down and administer the new medicine. Cory administers the treatment personally to Garth and the fleet captain seems at least partially cured, with no memory of what he has done. Kirk offers him his hand before Garth is taken away, and then notes that Spock could have found a more logical means of determining whom the real captain was.
Mr. Spock, um, letting yourself be hit on the head, and I presume you let yourself be hit on the head,
is not exactly a method King Solomon would have approved.