Star Trek (1966) season 1, episode 5
"The Enemy Within"
WRITER: RICHARD MATHESON
DIRECTOR: LEO PENN
AIR DATE: October 6 1966
During a routine survey mission on planet Alfa 177, technician Fisher has a fall and must beam back to the Enterprise for medical treatment. The transporter experiences some difficulties which Scotty concludes is the magnetic residue on Fisher’s jumpsuit. Deciding it is a minor issue, Scotty beams Kirk aboard and the two leave the transporter room. Moments later, another figure beams aboard. It’s another Kirk, and he looks… different.
"The Enemy Within" was written by Richard Matheson, who had some of his work had adapted into episodes of The Twilight Zone: "Nick of Time" and "Nightmare at 20,000 Feet" also starred William Shatner. Inspiration for the story came from The Strange Case of Dr Jekyll and Mr Hyde (1886) by Robert Louis Stevenson. The episode was directed by Leo Penn, father of Chris and Sean Penn. The novelisation was written by James Blish.
Duplicates are a common staple in science fiction, and this is only the first time Kirk will be duplicated during the course of his adventures. He will have an android double in "What Are Little Girls Made Of?", a shapeshifting madman will take on his form in “Whom Gods Destroy”, and an alien will briefly shift into his likeness in the theatrical movie Star Trek: The Undiscovered Country.
Uhura does not appear in this episode, but her voice is heard over the ship’s intercom system a few times during the story and before we jump into the usual trivia and other notable occurrences for the episode, there is one key factor in the episode which is usually a problem with many fans. While Scotty and crew attempt to repair the transporter, Sulu and the survey team are left on the planet surface while the temperature rapidly drops threatening to freeze them to death. Therefore the logical solution would be to send a shuttle and pick them up. Keep in mind that this is the fifth episode of the series to air (also fifth chronologically, strangely enough). The transporter was created for the show to avoid the need for any ship to planet transport and a shuttle had not yet been conceived of. It may even be possible that, in-universe, the Enterprise did not have shuttles on board that this event lead them to ensure that there were shuttle aboard for any future emergency. I know, it’s a stretch, but it’s all I’ve got.
Now, onto the points of interest:
Scotty uses a familiar device to scan the yellow substance on Fisher's uniform. It's the "cutie pie" radiation survey meter previously seen in "The Naked Time".
When Captain Kirk, followed by his evil counterpart, beam aboard the insignia is missing from his uniform. Costumes required daily cleaning according to union regulations and the insignia were removed before each cleaning. unfortunately the regular cleaning also lead to the costumes shrinking which became more and more noticeable as the series progressed. Later in the episode, Farrell is also missing the insignia from his uniform
Janice Rand's quaters are 3C 46 in this episode. In Charlie X, Rand's quarters were 3F 125.
This is the first chronological appearance of captain Kirk's green, wrap-around tunic. It was developed for this episode to easily differentiate between the 'good' Kirk and the 'bad' Kirk.
Although it is hard to see, an keen-eyed observer will be able to catch the first appearance of Captain Kirk's name, complete with middle initial 'T', posted on the wall outside his quarters.
A fantastic set piece, the tubes at the back of enginerring are configured from gradually smaller tubes giving the area a much larger appearance than the set could actually provide.
The triangular divider through which the 'evil' Kirk can be seen is appears to have been recycled from the first pilot "The Cage" and was also reused in "Where No Man Has Gone Before"
Spock was originally scripted to subdue the 'evil' Kirk with a Karate chop. Leonard Nimoy suggested a more logical and less violent method: the Vulcan nerve pinch. Shatner really sold it. Although this is its first chronological appearance, it was used previously in "The Naked Now".
The transporter component destroyed while battling the evil Kirk will be recycled in "The Devil in the Dark".
Unique to this episode, we can briefly see Sulu attaching his hand phaser into the pistol unit in order to use additional functionality. In this case, a broad phaser blast to heat the rocks, also seen only in this episode.
James Doohan was very careful to alway hide the fact that he was missing his middle finger on his right hand during the course of the series. His lack of a finger can be seen very briefly when he grabs at the 'evil' dog in the box.
McCoy delivers his most famous line "He's dead, Jim." in this episode. In "The Man Trap" he simply said "Dead, Jim".
While making a log entry, Spock refers to himself as 'second officer' rather than 'first officer'. An in-universe explanation is that he changed rank during the course of the series. Of course, this is another very thin explanation, but I've got nothing else.
During the final confrontation on the bridge, the scratches on 'evil' Kirk's face are on the wrong side. This was to maintain correct directional framing between him and his counterpart. The scene was film in the wrong direction and was flipped in editing.
The concept of a man facing his inner demons come to life before him is a great idea and very well portrayed by William Shatner. The 'good' Kirk slowly losing his command capabilities while the 'evil' Kirk giving into his base instincts makes an interesting flow while the secondary issues with Sulu and his team stranded on the planet surface facing death provides an increased level of urgency to correction the situation. The situation between Rand and 'evil' Kirk is uncomfortable, particularly when you consider that when reunited, the memories of both halves of Kirk will remain within the captain. He will have to live on with the guilt of his actions.