Star Trek (1969): S03E17 – That Which Survives


“That Which Survives” is the seventeenth episode of the third season of the American science fiction television series Star Trek.

Written by John Meredyth Lucas (based on a story by D.C. Fontana under the pseudonym Michael Richards) and directed by Herb Wallerstein, it was first broadcast 24 January 1969.

In the episode, the crew of the Enterprise visit an abandoned planet guarded by a mysterious woman.


The Enterprise discovers a planet whose young age is inconsistent with its atmosphere and biology. As Captain Kirk, Dr. McCoy, Lt. Sulu and geologist D’Amato begin to beam down, a beautiful woman appears in the transporter room, who touches the transporter technician, killing him instantly. As the landing party materialises, the surface of the planet is rocked by a violent tremor. Communication with the Enterprise is lost and they realise they are stranded.

At the same time, the Enterprise finds itself 990.7 light years from the planet. First Officer Spock orders the Enterprise back to the planet, and Dr. M’Benga determines the cause of the transporter officer’s death to be “cellular disruption”.

The landing party splits up and explores their surroundings. As D’Amato surveys a rocky area, he comes face-to-face with the woman who appeared in the transporter room. Addressing him by name and saying, “I am for you,” she touches D’Amato, killing him.

Chief Engineer Scott, sensing something “wrong”, orders Engineer Watkins to check equipment in a secluded area. The mysterious woman appears, kills Watkins, and disappears again. The ship begins to accelerate uncontrollably, and Scott discovers damage to the “emergency overload bypass”.

Back on the planet, a failed attempt to cut a grave for D’Amato proves that the planet is artificial. The woman appears to Sulu, who attempts to touch him but only brushes his shoulder with her fingertips. Sulu’s screams of pain bring Kirk and McCoy, who find him injured but alive. The woman touches Kirk’s shoulder without effect, and they conclude that she can only kill one person during each appearance.

Scott estimates that the ship will explode in 15 minutes if not brought back under control. Spock suggests a dangerous plan to manually cut the matter-antimatter fuel flow to the warp engines. Scott begins the procedure as the Enterprise passes warp 13.2.

On the planet, the woman appears again, announcing she is “for Kirk”, but Sulu and McCoy block her path. Questioned by Kirk, the woman says she is Losira, the station commander. She is alone, and her only purpose is to defend the planet from intruders. Kirk’s questions unsettle her and she vanishes without killing him. Strong power emanations then lead the landing party to a hidden entrance in a rock face.

The Enterprise has reached warp 14.1, threatening to tear her apart. Scott manages to stop the matter-antimatter flow at the last second, and the ship continues its course to the planet.

Passing into the hidden chamber, the landing party find a glowing cube, apparently a computer. Three copies of Losira enter, one each for Kirk, Sulu, and McCoy. As they approach, Spock and a security officer materialize, and, at Kirk’s command, destroy the computer. The three Losiras vanish.

A projected image of Losira then appears on a wall, informing her “fellow Kalandans” that a disease has killed the station’s personnel, and that the computer has been defending the station against intruders. McCoy surmises that the disease eventually wiped out the entire Kalandan species, and Spock suggests that the computer used images of Losira to do the job of defence. Kirk concludes that the landing party had survived because the reproductions were so perfect that they experienced regret about killing.

Star Trek TV Series

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Production & Filming Details

  • Director(s): Herb Wallerstein.
  • Writer(s): Michael Richards.
  • 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: 24 January 1969.
  • Running Time: 50 minutes.
  • Country: US.
  • Language: English.

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