Star Trek (1967): S01E25 – The Devil in the Dark


“The Devil in the Dark” is the twenty-fifth episode of the first season of the American science fiction television series Star Trek.

In the episode, Captain Kirk and Spock face off with a deadly subterranean creature. They are called to investigate a mining facility on a planet, and go on an away mission to the facility to try to resolve the issue.

This episode marks the first appearance of Doctor McCoy’s catchphrase, “I’m a doctor, not a [fill in the blank]!”


The starship Enterprise arrives at the pergium mining colony on planet Janus VI to help the colony deal with an unknown creature that has killed 50 miners and engineers, and destroyed equipment with a strong corrosive substance. Kirk, Spock, and McCoy meet with the mine supervisor, Chief Engineer Vanderberg and an engineer, Appel, who describe the amorphous creature and its behaviour. During the briefing, Spock’s attention is drawn to a silicon nodule on Vanderberg’s desk, which Vanderberg dismisses as a geological oddity. Suddenly, they are alerted to a problem in the colony’s main nuclear reactor, and find its guard killed and the main circulating pump stolen. Chief Engineer Scott rigs a temporary replacement, but the crude improvisation fails shortly thereafter. Either the missing part or a more-effective replacement must be found within 48 hours.

Captain Kirk and his security team begin to search for the creature. Spock, suspecting the creature may be a silicon-based lifeform, modifies their phasers to be effective against it. They encounter the creature, which has the appearance of molten rock, and fire upon it, breaking a piece of its skin off; the creature flees by burrowing through the rock wall at a rapid pace. Spock analyses the fragment, whose composition resembles asbestos. He deduces that it is able to burrow through solid rock by secreting the same corrosive substance that has killed the miners. They adjust their tricorders to scan for silicon-based life, and confirm that the creature is the only such lifeform for miles. Spock advises the captain that killing what appears to be the only creature of its species would be a crime against science, though Kirk believes that the creature has proven too dangerous to keep alive.

As all nonessential personnel are evacuated from the colony before the temporary pump fails, Kirk and Spock continue to search for the creature, happening upon a chamber containing thousands of the silicon nodules. The creature arrives, causing a cave-in that separates Kirk and the creature from Spock. Though Spock now urges Kirk to kill it, Kirk observes the creature has not attacked him, instead presenting its wound to him. Spock finds a way around the cave-in and joins Kirk, observing the creature. Spock attempts a mind meld with the creature, but perceives little but intense pain. The creature then etches the words “NO KILL I” into a rock, apparently having gained some knowledge of human language from the meld. Kirk wonders if this is a plea not to kill it or a promise it will not kill them. Spock attempts a second meld, and learns that the creature is called a Horta, and that its species dies out completely every 50,000 years, save for one individual that remains alive to protect the eggs of the next generation. The Horta, through Spock, tells them the location of the stolen pump.

Vanderberg and the remaining miners threaten to attack the creature when they see Kirk and McCoy caring for it, but Kirk explains that it was only protecting its eggs, the silicon nodules they have found. The miners fear the prospect of thousands of Horta, but Kirk convinces them that the Horta are peaceful and would be willing to cooperate with the miners.

Kirk, Spock, and McCoy return to the Enterprise, prepare to leave orbit, and learn from Vanderberg that the eggs have hatched and already the new Horta have found uncovered rich veins of pergium and other valuable metals. He adds that the miners are learning to overcome their aversion to the Horta. Spock remarks that the mother Horta felt similarly about humans, though she apparently found his pointed ears quite attractive.

Star Trek TV Series

You can find a full index of Star Trek TV series here.

Star Trek TV Series, Films, and Documentaries

You can find a full index of all Star Trek TV series, films, documentaries here.

Production & Filming Details

  • Director(s): Joseph Pevney.
  • Production: Desilu Productions (1966-1967) and Paramount Television (1968-1969).
  • Distributor(s): Paramount Pictures (1966-2006), CBS Paramount Television (2006-2007), and CBS Television Distribution (2007-Present).
  • Original Network: NBC.
  • Release Date: 09 March 1967.
  • Running Time: 50 minutes.
  • Country: US.
  • Language: English.

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.