is checking planet Alpha 177 for geological samples, a planet where the temperature drops down to 120 below. Geological Technician Fisher slips and falls into a yellow ore, cutting open his hand. He beams up to the ship to get it looked to, and the transporter briefly acts peculiarly. Kirk then beams up and staggers a bit, and Scotty leaves his station to help him to his cabin while Technician Walker goes to get a scanner. Once the room is empty, the transporter and another Kirk appears: a snarling bestial man who slinks out of the room.
Are you all right, Captain?
Yes, I'm all right. Just a little dizzy.
While the original weak Kirk is in his quarters, the bestial Kirk stalks into sickbay and demands brandy from McCoy, while Fisher looks on. The bestial Kirk then goes to Rand’s quarters. McCoy calls Spock who goes to the weak Kirk who claims McCoy is joking as he hasn’t been in Sickbay. Scotty then calls them to let them know that they beamed up an animal… and a minute later a savage version appeared, while the original is gentle and mild. They can’t beam up the landing party and realize that Kirk has been duplicated as well.
Two similar animals, but different.
One mean and fierce--
Some kind of savage, ferocious opposite.
Rand returns to her quarters to find the bestial Kirk, who tries to roughly seduce her. When that doesn’t work, he attacks her and she scratches his face fighting him off. She gets to the door and calls out to the passing Fisher to get security. The bestial Kirk goes after him and beats him into unconsciousness.
Call Mr. Spock!
Geological Technician Fisher.
Deck 12, section… arrgh!
Spock confronts the gentle Kirk who denies having left his cabin and they go to Sickbay. While the bestial Kirk slips into “his” quarters, Kirk and Spock confront Rand and point out Kirk doesn’t have any scratches. They figure there’s an imposter aboard and Scotty confirms that the yellow magnetic ore is responsible for the transporter malfunction. The surface temperature is dropping and the landing party is at risk, but the gentle Kirk can’t make up his mind what to do or what order to give. With Spock’s prompting, they order search parties out cross the ship. When gentle Kirk makes the announcement, the bestial Kirk goes berserk, then covers his scratches with makeup. He goes out into the hallway, meets Walker, takes his phaser, and then beats him unconscious.
If you see me slipping again,
are to tell me.
The landing party starts to freeze and the transporter renders power sources unusable. Gentle Kirk and Spock get word of the attack on Walker and figure the other Kirk would hide in Engineering. Gentle Kirk insists on searching the place with just Spock, and confronts his armed counterpart. The two square off until Spock uses the Vulcan nerve pinch and renders the bestial Kirk unconscious, causing him to spastically fire his phaser into some power conduits.
You can't hurt me.
You can't kill me.
You can't. Don't you understand?
I'm part of you.
You need me.
I need you.
While the landing party continues to freeze to death, in Sickbay Spock considers the possibilities of examining the captain’s “good” and “evil” sides, and the fact he needs both of them to effectively command. Scotty lets them know that the power conduits affected transporter control and it will take a week to fix.
Could you find a long rope somewhere
and lower us down a pot of hot coffee?
I'll see what we can do.
Rice wine will do, if you're short on coffee.
The bestial Kirk starts to die due to the replication process and his own fear, the gentle Kirk uses his intellect to convince him to hang on. He’s reluctant to take back his “evil” side but it’s clear the two will die apart. Meanwhile, Scotty and Spock repair the transporter and use the animal as a test subject, but it dies after being rejoined into one being. Spock believes it lacked the intellect to comprehend the process and died of shock, while McCoy warns the process may be lethal.
The shock of putting him back together
was too much for him. He's dead, Jim.
The gentle Kirk finally decides to undergo the reintegration and goes to get his counterpart. The counterpart easily knocks him out, scratches the “good” Kirk’s face, then goes to the bridge. He orders them to abandon the landing party and leave orbit, much to everyone’s surprise. The gentle Kirk and McCoy arrive and Spock and the others let the two Kirks resolve the matter. The bestial Kirk is terrified of “going back” but the gentle Kirk convinces him it’s necessary and takes the phaser. They undergo reintegration and the procedure is a success. They beam up the landing party just in time, while Kirk admits he’s faced a side of himself no man should ever see. Later on the bridge, Kirk thanks Spock and Rand, and Spock notes to Rand that the counterpart had some “interesting qualities.”
The, uh, impostor had some interesting qualities,
wouldn't you say, Yeoman?