Dagger of the Mind
Star-trek tos-season1-9
Season 1, Episode 9
General Information
Series Star Trek
Air date November 3, 1966
Written by S. Bar-David
Directed by Vincent McEveety
Episode guide
Previous Next
Miri The Corbomite Maneuver
Star Trek episodes


The crew of the USS Enterprise respond to a prison riot at an insane asylum planet.

Plot Summary

Stardate: 2715.1 [1]Dr. Simon with maskThe Enterprise crew preparing beam some drugs to the Tantalus Penal Colony once the penal colony's barrier is turned off. When the Penal Colony cargo comes aboard the ship, a strange man sneaks out of the cargo and knocks out one of the men. Nyota sounds the alarm about the intruder. The strange man evades the search team and enters the bridge. When the prisoner make demands, Captain Kirk refuses to answer them. From behind, Spock knocks out the prisoner. In the sick bay, Captain Kirk and Dr. McCoy observe the prisoner, Dr. Simon van Gelder, struggle to explain himself. They learn that Dr. Simon was an assistant to Dr. Tristan Adams, Director of the Tantalus Facility. While Captain Kirk speaks to Dr. Adams, Dr. McCoy states that he cannot believe Dr. Adams for unknown reasons. Captain Kirk states that Dr. Adams has revolutionizes prisons and making them more human. Dr. Adams asks Captain Kirk to drop Dr. Simon off at a superior medical facility.

Then, Captain Kirk asks Dr. Adams to investigate their facilities after Dr. McCoy voices his concerns. Dr. Adams agrees and allows the Enterprise to send a small group. Since Dr. McCoy cannot leave Simon in the sick bay, he tells Captain Kirk to go with Dr. Helen Noel to the penal colony. Arriving to the penal colony, Dr. Adams introduces Lethe, a changed woman, to Captain Kirk and Dr. Helen. Throughout their tour, Captain Kirk spots a man who is staring out of the window. Back in sick bay, Simon tries to tell Sulu and Dr. McCoy about a neural neutralizer. At the meantime, Dr. Adams explains about the neural neutralizer and its benefits. Though, Captain Kirk expresses his skepticism since Dr. Adams has not explained what had happened to Simon. Dr. Adams states that Simon became insane when blasted with the full intensity of the beam and says that the machine is harmless at low intensity. Then, Spock reports to Captain Kirk that Simon is warning him to stay away from Dr. Adams. Captain Kirk tells his men that he will spend the night here. Then, Simon freaks out and tells them to not let Captain Kirk stay over there. [2]Spock performs mind meldDr. McCoy urges Spock to find the truth by having Spock mindmelds with Simon. Meanwhile, Captain Kirk asks Helen to come with him to take a closer look at the neural neutralizer machine. In the operating room, Captain Kirk has Helen use the neural neutralizer on him to observe the effects. During the experimentation, Helen and Captain Kirk finds out that patient is doing what the operator wants them to do. When Captain Kirk asks Helen to ask him something unusual, Helen tells Captain Kirk to recall that they are having a romantic encounter at the Christmas Party. Suddenly, Dr. Adams take the controls from Helen. After Dr. Adams brainwashing him that Captain Kirk is in love with Helen and lost her, he commands Captain Kirk to drop his communicator and taser. Captain Kirk struggles to communicate to enterprise.

Later in Captain Kirk's room, Captain Kirk tells Helen to crawl into the ventilation ducts to shut off the power. While Dr. Adams is forcing Captain Kirk to tell him where Helen is, Helen makes her way to the power room. She sneaks past the guards and shuts down the power. Captain Kirk regains his senses and knocks out Dr. Adam and his assistant. At the same time, Helen kicks one of the men into the equipment, resulting in his electrocution. Spock beams down and turns off the force field. When Spock turns on the power, the neural neutralizer turns on and blasts Dr. Adams. When Helen returns, Captain Kirk embraces and kisses Helen until Helen reminds him about Dr. Adams. Captain Kirk and the others find Dr. Adams dead from the neural neutralizer.

Production Notes

The background of Penal Colony Tantalus is the lithium cracking station on Delta Vega from Star Trek: Where No Man Has Gone Before. Though, the background is altered in the remaster version.

The Vulcan mind meld is first introduced in this episode. The writers did not want it to be interpreted as a medical technique since Spock has no medical credentials. Also, the writers had to work around NBC's standards and practice warnings to avoid hypnotizing the viewers.

Ad blocker interference detected!

Wikia is a free-to-use site that makes money from advertising. We have a modified experience for viewers using ad blockers

Wikia is not accessible if you’ve made further modifications. Remove the custom ad blocker rule(s) and the page will load as expected.