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That Which Survives

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Episode no.  Season 3 Episode 17
Story by  Michael Richards
Featured music  Fred Steiner
Directed by  Herb Wallerstein
Teleplay by  John Meredyth Lucas
Cinematography by  Al Francis

"That Which Survives" is the seventeenth episode of the third season of the original science fiction television series, Star Trek, first broadcast January 24, 1969, and repeated July 29, 1969. It was written by John Meredyth Lucas, based on a story by D.C. Fontana under the pseudonym Michael Richards and directed by Herb Wallerstein.


In this episode, the crew of the Enterprise visit an abandoned outpost guarded by a mysterious computer.


The Enterprise discovers a planet that appears young compared with the evolutionary stage of its surface life forms. Captain Kirk, Dr. McCoy, Lt. Sulu and geologist D'Amato, prepare to beam down to the planet to investigate. In the midst of dematerializing, they see a beautiful woman appear in the transporter room and try to stop the landing. She touches the baffled transporter technician, Ensign Wyatt, killing him instantly.

As soon as Kirk and the others materialize on the planet, the surface is rocked by a violent tremor. The Enterprise is also jolted as it is thrown 990.7 light years away from the planet by an unknown force. Dr. M'Benga examines Wyatt and learns his death was caused by complete cellular disruption.

The landing party loses communications with the Enterprise and they realize they are stranded. They split up and begin to scout around. As D'Amato surveys a rocky area, he comes face-to-face with the woman who appeared in the transporter room. Strangely, she says "I am for you" and knows his name. When she touches D'Amato, he too falls dead.

First Officer Spock orders the Enterprise back to the mysterious planet. En route, Chief Engineer Scott reports a vague feeling that the ship "isn't right" and orders Engineer Watkins to check equipment in a secluded area. The mysterious woman assassin appears again, kills Watkins and sabotages the Emergency Overload Bypass.

On the planet, while burying D'Amato, Kirk discovers that the planet's surface is highly resistant to phaser fire. Kirk and McCoy sleep and Sulu takes the first watch. The woman appears to Sulu, and he discovers she is invulnerable to phaser fire. He trips on a rock so she only brushes his shoulder briefly 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. They discover that the woman can only kill one specific person during each appearance.

Meanwhile on the Enterprise, the ship's speed increases uncontrollably. Scott discovers the woman's sabotage and estimates that the ship will explode in 15 minutes. Spock and Scott devise a dangerous plan to manually cut the matter-antimatter fuel flow to the warp engines. Scott begins the risky repairs as the Enterprise passes warp 13.2.

On the planet, the three narrowly avoid death when Kirk's phaser suddenly goes into overload and explodes. The woman appears "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 conversation unsettles her and she vanishes without killing him. The landing party subsequently discover the entrance to a room that is the source of the strong power emanations and enter.

Back on the Enterprise, Scott manages to stop the matter–antimatter flow at the last second, saving the ship and restoring control.

Inside the station, the landing party finds a cube-shaped computer. It projects three copies of Losira, one each to kill Kirk, Sulu and McCoy. Before they can kill the landing crew, Spock and a security officer beam into the room. At Kirk's command, the security officer shoots the computer and the three assassins disappear.

A viewscreen then displays a pre-recorded message by Losira, a Kalandan who had been the last survivor at the outpost. She had programmed the computer to defend the outpost and it used her likeness for the assassins. The recorded Losira explains that while creating the planet they also created a deadly organism. McCoy surmises that the disease spread throughout the Kalandan race and drove them to extinction long ago. Kirk suggests that the landing party had survived only because the image of Losira was so complete that it experienced regret about killing.


The original story outline was written by D.C. Fontana under the pseudonym Michael Richards. In this outline, called "Survival", Losira is more brutal, encouraging the crew to turn on each other and fight.


That Which Survives Wikipedia