Star Trek (1966–1969)
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Dagger of the Mind 

Kirk and psychiatrist Helen Noel are trapped on a maximum security penal colony that experiments with mind control and Spock must use the Vulcan mind-meld to find a way to save them.



(as S. Bar-David), (created by)

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Episode complete credited cast:
Susanne Wasson ...
John Arndt ...
Ingenieur Fields
Larry Anthony ...
Ed McCready ...
Eliezer Behar ...
Eli (as Eli Behar)


After a psychologically disturbed patient from the Tantalus penal colony, Dr. Simon Van Gelder, manages to escape to the Enterprise, Dr. McCoy begins to suspect that something is amiss on the colony. Captain Kirk and Dr. Helen Noel beam down to the planet to investigate. Written by garykmcd

Plot Summary | Plot Synopsis


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Release Date:

3 November 1966 (USA)  »

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Technical Specs


Sound Mix:


Aspect Ratio:

1.33 : 1
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Did You Know?


This episode marks the first appearance of the Vulcan mind meld. The final shooting draft of this script had Spock placing his hands on Van Gelder's abdomen while performing the mind meld. According to The Making of Star Trek, the mind meld was developed as an alternative to the scripts use of hypnosis to stabilize Van Gelder. They did not want to inaccurately depict hypnosis as a medical technique. Nor did they want to shoehorn into the script a pretext that Spock was qualified to act as a hypnotist in a medical capacity. Lastly, they did not want to risk accidentally hypnotizing viewers at home. See more »


When Kirk and Spock are discussing the identity of the penal colony escapee (Dr. van Gelder), the camera angle goes back and forth between them. When looking at Kirk, the background wall (correctly) curves to the right, past communications and the turbolift. But the reverse angle at Spock *also* curves to the right; however, it should curve to the left, towards the main viewscreen. See more »


Mr. Spock: What is our name? Who are we?
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User Reviews

The Overly-Trusting Kirk
25 April 2014 | by (United States) – See all my reviews

James Gregory manages a penal colony for the criminally insane. When one of his patients, the former manager, Van Gelder, gets on board the Enterprise. He acts mad, and Kirk doesn't listen to him. Gregory tells Kirk that he is welcome to come to the surface and check out the story that Van Gelder is spouting. Spock, meanwhile, continues to investigate the invader, who doesn't get much more lucid. Kirk insists that a person with great knowledge of the mind go to the surface as well. She is a gorgeous Brunette who is apparently one of the Captain's previous conquest. Dr. Adams (Gregory) shows Kirk and the young woman a machine that scans and corrects brain functions. Kirk falls for the charade and soon finds himself in grave danger, having his own consciousness messed with. We soon find out that the inmates are literally running the asylum. We have to ask why, with all the medical knowledge that should have evolved, people are being treated this way, it begs that question. The gullibility of Kirk gets him in trouble many times during this series and this is another time when his judgment is respected.

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