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Season One:
-1: "The Cage"
-2: "Where No Man Has Gone Before"
-3: "The Corbomite Maneuver"
-4: "Mudd's Women"
-5: "The Enemy Within"
-6: "The Man Trap"
-7: "The Naked Time"
-8: "Charlie X"
-9: "Balance of Terror"
-13: "The Conscience of the King"
-16: "The Menagerie"
-20: "The Alternative Factor"
----: _Time Travel Season 1
-21: "Tomorrow is Yesterday"
----: _Prime Directive Origins
-22: "The Return of the Archons"

-23: "A Taste of Armageddon"
-27: "Errand of Mercy"
-28: "The City On the Edge of Forever"
-29: "Operation -- Annihilate!"
-Season 1 Rankings

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The Enemy Within

(Star Trek story #5 in production order)
  • written by Richard Matheson
  • directed by Leo Penn
  • music by Sol Kaplan

The Enemy Within

Star Trek came up with one of its best original concepts for a story here in this episode, and then milked it for most of its potential. The central idea of letting the transporter create two versions of Kirk, each with opposite aspects of his personality, was an excellent way to use science fiction to explore the human condition. Additionally, this episode is virtually the template that shows how Star Trek will approach this central explorative reason for its existence using the cast of characters that it had finally settled on. The infamous Kirk-Spock-McCoy trio begins to function as a unit here for the first time.

Story Mechanics

Early sections of the episode paint a picture of space exploration as an everyday aspect of life aboard the Enterprise, while the jeopardy is only shown and known to the audience and to Captain Kirk's log entries from an unknown future time. A very good way to go in this case. William Shatner really throws himself into his dual role with a lot of energy, gusto, and bravery, which goes far to really sell the concept and make the episode one of early Star Trek's best successes.

There's a nice logic here in starting the episode on the planet, and using the threat of Sulu and his comrades freezing to death while waiting for the transporter problems to be worked out. It puts a good bit of time pressure on the main drama. Of course, fans subsequently wonder why the Enterprise didn't just send a shuttlecraft down to pick them up. In production terms, shuttlecraft hadn't yet been thought up. In story terms, Vonda N. McIntyre fabricated a reason for her novel of this crew's first coming together... along the lines of the Enterprise's new shuttles not quite being ready before they had to launch. It works for me.

So, we get another early episode that takes place mostly on the Enterprise, which is a new enough environment at this stage that it remains quite interesting. This time, production design focuses mainly on adding the engine room to its labyrinth of standing sets for the ship. This room is shot in some unusual ways, as the script calls for a game of cat and mouse to be played out there, ensuring that the room gets built and gets showed off a bit. A worthy thing to do in the fifth episode. Additionally, the sequence becomes something of a highlight for the episode, both dramatically and musically, and culminates with the first example of Spock's Vulcan nerve pinch, plus a phaser blast for added excitement. Awesome.

"The Enemy Within" is graced by one of the real standout musical scores of the first season, with many cues having become extremely familiar to fans of the show after hearing those cues get used on so many subsequent episodes. Sol Kaplan here virtually defines the template for scoring the act openings with quotes of Alexander Courage's main fanfare over shots of the ship orbiting the planet. We also get many great, inventive action cues and highly dramatic passionate tension builders, as well as a few really nice quieter pieces for lighter moods. This score was a very important ingredient in defining the unique sound that Star Trek's music was later known for. Magnificent.

music by Sol Kaplan

The episode quickly cycles through mostly-visual exposition, mystery, and a good bit of action in its first half. Surprisingly, today's "villain" is captured and strapped down in sickbay for a good deal of the second half, yet the drama doesn't suffer at all. We have simply shifted from doing the obvious action-adventure beats to focusing on the character questions and philosophical implications, while Sulu's survival predicament and Scotty's transporter repair efforts receive their due.

And in fact, this second half features the episode's real gold. Spock and McCoy get their first really significant debate of the series here, as they get to examine what has really happened to the Captain, and what his different halves are like.

Multiple Polarities, headed for Integration

In reality, there are hundreds of different dimensions in anyone's character that could be polarized and separated for examination - this is virtually a template for some spiritual "new age" models of what living beings try to work out as they evolve. This episode's classification of so many traits in terms of "good" and "evil", each with its own version of Kirk in which to be embodied, is actually a bit arbitrary. But, I think the definitions here are still highly useful, and make a good entertaining drama. I'm okay with embracing this variation, while knowing that many other variations could be equally valid.

Perhaps the main difference is best described as an aggressive and desiring side versus a calmer and more nebulous side. Interesting is how each side is shown to contribute to James Kirk as a whole and effective being. Spock goes to bat for the "dark" side, showing that over here lies the desired trait of decisiveness, an important pre-requisite for being Captain. McCoy eventually comes to notice a great strength of Kirk's apparently weaker "nice" side - the dark version houses most of his fear (and this is important because fear is a PRIME motivator of darker or undesirable action). Meanwhile, it is his lighter side that contains his essential bravery and courage. While Evil Kirk is strapped down in sickbay, Good Kirk gets the material he needs to showcase his strengths and weaknesses.

Interestingly, some of the newly discovered dualities in quantum physics are also paralleled here, and these might offer us the most non-judgmental ways of viewing the character split yet. In many ways, the dark Kirk embodies the particle, the decisiveness of a chosen form and a path cut off from all others. Meanwhile, the lighter Kirk expresses the waveform, the endless possibilities in which any and all things are considered and held of equal value, but in which one's purpose may get lost or muddled. Thus, "The Enemy Within" remains fascinating and relevant long after the time in which it was made - passing the test of truly great art.

Interesting also are the examples, exaggerated in this episode, of Good Kirk listening to the opposing viewpoints and recommendations from both Spock and McCoy, while it is up to him to decide what to do. We will see this trio of characters go through this dynamic on many different subjects with many different situations, yet here, Good Kirk really struggles with the decision where the composite whole Kirk would quickly make up his mind and allow everyone to proceed with their tasks.

And it is to the episode's great credit that the ideal state to strive for at the end is not to polarize towards the "good" side, but instead to aim for balance, and to integrate all aspects within oneself. That's a great and profound statement to make on the human condition, and this episode does it very, very well. Hats off.

Workplace Friction

If there is one caveat to the episode, it comes through in the subplot with Yeoman Rand. It is perhaps a questionable move to include such an overt attack on her by the lead figure of the series, and to portray it as graphically as they did. On its own, being something few people would really appreciate seeing, it seems to be dragging the episode's ranking down a few notches, until later sections of the story work so well to elevate it back up to classic status. On the other hand, should we consider it a brave choice for the show to make, demonstrating what the dark Kirk is capable of and why we should fear him, in ways that no amount of shouting and brandy drinking could do all on their own?

I think the real test for this scene is in how the situation is dealt with in the end. The scenes of Rand and Fisher telling the story to Spock and McCoy feel quite realistic in how they were handled. Indeed, though this is only Rand's second story in production order, she exhibits a reluctance in reporting him because she likes and respects the captain, and hindsight from future episodes tells us she might already have a bit of a crush on him, which would have been a more interesting thing to explore. But Star Trek in general needs to aim for a higher ideal.... indeed it has been convincingly said that one of the great archetypal appeals of the entire franchise is its depiction of "the ideal workplace", where there is no thought of discrimination for race or gender, and the work that people do is profound and important and noble. On that note, I think that going as dark as they did with Rand's situation demands that it be dealt with a bit better in the final wrap up. She has something she wants to say to Kirk on the bridge at the end. Kirk seems a bit too arrogant in assuming that he knows what she is about to say before cutting her off. I think he'd come off much better if he would be a good listener instead. Following that, Mr. Spock has a really CHEESY comment to offer her. That combination is a bit too insensitive to allow this episode to sit as well with me as it otherwise seemed destined to. If you really want to end on comedy and implied unspoken desires, it's better to not have gone to quite such an extreme earlier on. Or, if you do go that dark, then be a bit more sensitive in coming back into the light. Exactly how comfortable is Rand with her captain after the fact? How well can we expect them to work together? To what extent does she prefer to say something to him on a bridge full of people, rather than in private? I'd have felt much better if he and Spock would have let her express her thoughts on the matter then and there.

Other minor points of note include the fact that actor Ed Madden returns from "The Cage", apparently playing the same geologist on the crew, now named Fisher and sporting a different hair style and uniform. Uhura is heard but not seen in this episode, while she swaps out her uniform for another of the correct colour. We also get the first of McCoy's infamous "He's dead, Jim" lines, this time referring to the unfortunate little canine creature who also suffers the transporter splitting effect and can't quite handle the re-integration process. As a child, I totally bought that this was an alien creature, and even though it's far more obvious to me now how the creature was achieved, I think it's still a good low-tech realization. I additionally like the touch of consistency when the "good" version of the creature shows the same concern and compassion for his negative alter-ego self as William Shatner does for his own duplicate - a nice animal acting moment.

Well, Star Trek can largely rack up another very good one as its fifth episode. Writer Richard Matheson had already become one of the most prolific episode writers on "The Twilight Zone", and has certainly delivered quite well in what I believe is his sole contribution to Star Trek. Well done.

Read the next Star Trek review: "The Man Trap"

"The Enemy Within" is available in the following themed DVD box set
with optional audio commentary by "Enterprise" writers Judith and Garfield Reeves-Stevens.

This version features only the upgraded CGI optical shots of the ship in orbit, not the original filmed optical shots.
Click on the Amazon symbol for the desired disc format and location nearest you for pricing and availability:

Star Trek Fan Collective:
Alternate Realities

Region 1, NTSC, U.S.
Region 1, NTSC, Canada
Region 2, PAL, U.K.

A series of "Fan Collective" DVD Sets are also on the market, offering a sampling of episodes from across all Star Trek series and spinoffs. "Alternate Realities" is apparently the first of those to offer the remastered versions of original Star Trek episodes, with the upgraded special effects. Those who are dubious about this process may wish to try this less-expensive-than-a-full-season set to see what all the fuss is about.

We also get some long-awaited audio commentaries on a few of the episodes, a welcome rarity for Star Trek's live-action TV shows, although some British fans have complained that the audio commentaries are missing from the Region 2 version.

20 episodes @ 43-51 minutes each:
  • Mirror Universe
    • TOS: "Mirror, Mirror"
    • DS9: "Crossover" (with director's commentary)
    • DS9: "Through the Looking Glass"
    • DS9: "Shattered Mirror"
    • Ent: "In a Mirror, Darkly (Part 1)"
    • Ent: "In a Mirror, Darkly (Part 2)"
  • Parallel Dimensions
    • TOS: "The Alternative Factor"
    • TNG: "Parallels" (with writer's audio commentary)
  • Twisted Realities
    • TOS: "The Enemy Within" (with audio commentary)
    • TOS: "Turnabout Intruder"
    • TNG: "Frame of Mind"
    • Voy: "Shattered"
  • Alternate Lives
    • TNG: "Yesterday's Enterprise" (with director's audio commentary)
    • TNG: "The Inner Light"
    • DS9: "The Visitor"
    • Voy: "Before and After"
    • Voy: "Timeless"
    • Voy: "Course: Oblivion"
    • Ent: "Twilight" (with writer's audio commentary)
    • Ent: "E2"
  • Special Features
    • Mirror Universe: Part 1 (14 min.)
    • Mirror Universe: Part 2 (5 min.)
    • Parallel Dimensions (7 min.)
    • Twisted Realities (13 min.)
    • Alternate Lives: Part 1 (11 min.)
    • Alternate Lives: Part 2 (15 min.)
  • Audio Options (may vary according to region)
    • English
    • Español
    • Portugues

More standard versions of "The Enemy Within" are also available on DVD and Blu-Ray.
Click on the Amazon symbol for the desired disc format and location nearest you for pricing and availability:

Star Trek Season One "Purist" Standard DVD Box Set:

Watch the legend develop from its infancy. Set contains 29 episodes from the first season in their original wacky broadcast order, including "The Menagerie Parts 1 & 2" which used footage from the original unaired pilot "The Cage". However, "The Cage" itself is only included with the Season Three Box Set.

As someone interested in researching how the episodes actually looked and sounded originally, and when and exactly how certain musical cues first debuted, this was the DVD set for me, and it remains the most untampered-with full-season collection of Star Trek out there. Unique extras include pure text commentaries on select episodes. Sadly, these sets are starting to become rare, and prices are now rising as these become collectors' items....


DVD Canada


Standard DVD Extras include:

  • original restored broadcast versions of the 29 episodes.
  • "The Birth of a Timeless Legacy" documentary (24 min.)
  • Text only commentary by Denise & Michael Okuda on "Where No Man Has Gone Before", "The Menagerie Parts 1 & 2", and "The Conscience of the King".
  • "To Boldly Go" featurette (19 min.) discussing
    "The Naked Time", "City on the Edge of Forever",
    "The Devil in the Dark", and "The Squire of Gothos".
  • "Reflections on Spock" featurette (12 min.)
  • "Sci-Fi Visionaries" writing featurette (17 min.)
  • "Life Beyond Trek: William Shatner" featurette (10 min.)
  • "Red Shirt Logs" Easter Eggs (7 min. total)
  • Photo Log (still menus)
  • Original Trailers for every episode (1 min. each)

Standard DVD Remastered with CGI:
DVD/HD Combo R1
DVD/HD Combo R1
DVD/HD Combo R2
Standard DVD only R2

The Original Series Remastered Sets

The re-mastered Star Trek sets are more readily available, and in addition to picture and sound quality restoration, liberties have been taken with "upgrading" the episodes. Most famously, new CGI effects and optical shots have replaced many space scenes, matte paintings, and phaser effects. Unlike similar upgrades applied to select Doctor Who DVD releases since 2002, the CGI effects cannot be turned off to see the original effects. The kicker for me comes from reports that the episodes have been rescored with new music. Interesting, funky, but since it's primarily the original music I'm after in the first place, this was not the set for me.

Another curiosity: Season One was released on double-sided discs, with standard DVD on one side and HD on the other. Reportedly, not all extras are accessible on the standard DVD side. However, by the time the remastered versions of seasons two and three were released, HD had clearly lost the standards war to Blu-Ray, and so seasons two and three "remastered" offer standard DVD only yet again.

Adding to the bizarre formatting is the very gimmicky, awkward packaging that is prone to damage both during shipping and with light usage. The season 1 set fares better than its counterparts for seasons 2 or 3 though, in having some interesting bonus features not found on any other season one Star Trek set:

DVD/HD Combo Season 1 Exclusive extras:

  • Starfleet Access interactive trivia plus picture-in-picture interviews for "The Galileo Seven" (HD version only).
  • "Beyond the Final Frontier" History Channel documentary (SD, 90 min.) with host Leonard Nimoy.
  • Trekker Connections interactive DVD game (SD side)
  • Star Trek online game preview (SD, 3 min.)

Season One - Blu Ray

  29 episodes @ 51 minutes
Star Trek sets are now available on Blu Ray. Picture and sound quality restoration has gone up yet another notch since the remastered version, as have the liberties taken with "upgrading" the episodes. Once again, even newer CGI effects and optical shots have replaced many space scenes, matte paintings, and phaser effects.... but this time the upgrades have the same respect and user-functionality applied to select Doctor Who DVD releases since 2002, as the CGI effects can now be turned off to see the original effects. Good show. It seems that the music has still been tampered with too much for my liking though.

Blu-ray U.S.

Blu-ray Canada

Blu-ray U.K.

Blu-ray features add:

  • option to watch episodes with original or new CGI effects.
  • Spacelift: Transporting Trek into the 21st Century featurette (HD, 20 min.) covering the restoration, CGI effects, and music upgrades.
  • Starfleet Access - Okuda interactive trivia plus picture-in-picture interviews on 6 episodes:
    • Where No Man Has Gone Before
    • The Menagerie Part 1
    • The Menagerie Part 2
    • Balance of Terror
    • Space Seed
    • Errand of Mercy
  • Behind-the-scenes 8mm home movies (HD, 13 min.) from Billy Blackburn (Lt. Hadley / Gorn)
  • Kiss 'N tell: Romance in the 23rd Century (8 min.)
  • Interactive Enterprise Inspection (HD)
  • plus all documentaries, featurettes, and episode promos from the "purist" standard DVD set listed far above.

Article written by Martin Izsak. Comments are welcome. You may contact the author from this page:

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Read the next Star Trek review: "The Man Trap"

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