Star Trek: Season 1, Episode Twenty-Five “The Devil in the Dark”

Stardate: 3196.1 (2267)
Original Air Date: March 9, 1967
Writer: Gene L. Coon
Director: Joseph Pevney

“There’s nothing more dangerous than a wounded animal.”

Rating: 5 out of 5.

A strange creature has been killing people deep in the underground craggy tunnels of a “pergium” mining facility on Janus VI –over the span of three months the creature has already killed 50 people. The Enterprise receives a distress call and makes haste for Janus VI where Kirk and Spock beam down to the production station meet with Chief Engineer Vanderberg (Ken Lynch). The facility recently opened a new lower-level layer of ore-rich with pergium as well las other minerals like uranium. Spock makes note of a highly unusual geologic formation in Vanderberg’s office –a perfectly round “rock.” While they are speaking, the nuclear reactor is attacked by the creature. It kills one man (a red shirt) and also steals a vital circulating pump without which the nuclear reactor might fully melt down. Scotty rigs a temporary substitute part for the reactor while Kirk and Spock investigate. They quickly uncover the blob-like molten rock creature, a silicon-based life form (rather than a carbon-based being) made of an asbestos-like material. Apparently, it is capable of releasing an acidic corrosive substance which allows it to easily burrow through a labyrinth of underground tunnels.

While interactions are initially hostile, Spock attempts a mind meld with the creature where we learn it is called a “Horta.” Spock picks up deeply held pain by the Horta. It is the lone species of its kind –the Horta species dies out every 50,000 years except for one which remains behind as a protective mother figure to grow its own eggs for the next generation (these are the strange “rocks” Mr. Vanderberg was keeping in his office). Through the mind meld the Horta creature learns basic human language and it sears a message on a nearby rock: “No Kill I.” Kirk and Spock uncover thousands of Horta eggs just as the miners storm onto the scene to attack the Horta. Spock cautions Kirk against killing the Horta, calling it “a crime against science.”

With newfound sympathy for the Horta, Kirk prevents the miners from attacking and he successfully persuades them of the Horta’s innocence. He explains that the Horta was merely trying to protect its eggs which were stolen or damaged by the miners, and instead of slaughtering the creature, perhaps the miners can use the Horta’s tunneling experience to find new sources of pergium. In the end, back aboard the Enterprise, Chief Engineer Vanderberg radios Kirk to thank him and inform him that the eggs are hatching. Kirk and Spock muse about his ears while the Enterprise speeds away at Warp 2.

My Thoughts on “The Devil in the Dark”

In recent episodes like “The Return of the Archons” or “A Taste of Armageddon,” we sometimes wonder to what extent Starfleet exists merely to serve the imperial whims of the Federation in Star Trek, however I love episodes like “Devil In The Dark” an episode which truly showcase the benign efforts of Starfleet. Just because a creature appears strange, hostile, and vicious at first does not necessarily mean we cannot attempt to understand them –the continuum of consciousness extends beyond carbon-based beings. Star Trek exposes our natural impulse to destroy creatures that are foreign and scary. Also we are reminded of the cold, disrespectful nature of industry as it arrogantly plunges into regions unknown. Their destructive efforts of the Janus VI mining facility brings about unanticipated consequences and enemies. It is wonderful to aliens of all shapes and forms in Star Trek, not merely humanoid species which are replete throughout the series. Also it is terrific to see a nod to nuclear power in this episode.


This episode was written by producer/writer Gene L. Coon (1924-1973), a key member of the creative team in the first and second seasons.

Director Joseph Pevney (1911-2008) is tied with Marc Daniels for most TOS episodes directed. This was his first directed episode in the series after being brought onboard by Gene L. Coon.

Star Trek Trivia:

  • This episode marks the first appearance of Doctor McCoy’s catchphrase, “I’m a doctor, not a …” In this case, he says, “I’m a doctor, not a bricklayer!” when Kirk orders him to heal the Horta.
  • What is pergium? It is a fictional ore in the Star Trek universe apparently used to power nuclear reactors.
  • NBC announced that Star Trek will be renewed for a second season next fall, during the closing credits of this episode on 9 March 1967.
  • The original name of the planet in this episode is Thetis Six. However, “Thetis” was already given to a mid-19th century asteroid so the name was changed to Janus VI instead.
  • William Shatner received a call on the set of this episode from his mother informing him that his father had died. The crew was ready to shut down production, but he insisted on continuing. Shatner later identified this as his favorite episode and Gene Roddenberry listed it in his top ten episodes, as well.
  • The unbroken Horta eggs were actually toy bouncing balls painted gold.
  • Successful authors like Michael Chabon and Arthur C. Clarke have offered fond memories of this episode.
  • The Horta was played by stuntman and acrobat Janos Prohaska, who also designed the costume. He was promised that if he created a good enough costume, the producers would rent it and pay Prohaska to play the part. Episode writer Gene L. Coon was convinced of the costume’s effectiveness after an impromptu demonstration by Prohaska in the studio.

Click here to return to my survey of the Star Trek series.

2 thoughts on “Star Trek: Season 1, Episode Twenty-Five “The Devil in the Dark”

  1. The Devil In The Dark is one of the few classic Star Trek episodes that can still retain most of its original impact. It is indeed a timeless and vital morality tale. Thank you for your review and some of the best Trek trivia that I’ve read on your site. 🖖🏻🖖🏼🖖🏽🖖🏾🖖🏿

    Liked by 2 people

    • Many thanks Mike. Ive been playing around with the format of my site lately, we’ll see where I settle with it. But excited to dive back into Star Trek again. Thanks again for all your positive commentary and all the best to you and yours.

      Liked by 1 person

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