The Federation starship Voyager is orbiting the Mari homeworld. The Mari are a race of telepaths. As the ship's crew trade for supplies and finding it difficult to haggle and bargain with mind readers. While all of this is happening, Lt. Commander Tuvok and the city's Chief Examiner, Nimira, talk of security and maintaining order. Nimira states her job is slowly becoming obsolete, with their methods of crime prevention, there has been no violence in their society for years. She is one of the last security officers among the Mari; sharing a curiosity regarding crime and punishment in their own society Tuvok offers to transport her aboard Voyager to demonstrate their ways of security enforcement. While Captain Janeway and her half-Klingon Chief Engineer B'Elanna Torres are negotiating for a resonator coil, someone bumps into Torres, momentarily irritating her. She calms herself, shrugging it off as an accident. Moments later they run over to find the man who bumped into Torres beating another man bloody. The beaten man is severely injured as Janeway stops the aggressor. The aggressor seems surprised at himself and says he does not know why he did that. While aboard Voyager, Namira is puzzled about the ships brig and the concept of incarceration as a form of punishment only to be called back to the surface regarding the attack. After questioning the crew, Nimira, the Mari constable, determines that B'Elanna's angry thoughts earlier that day was transmitted telepathically to the aggressor, and thus she is the more guilty of the two. She is sentenced to undergo memory modification to remove the thought, as is the aggressor. Janeway protests, as the modification process carries the risk of neurological damage. Before Janeway can unearth enough evidence to try to get Torres out, another attack occurs with the same memory, indicating that it is still in circulation. Unfortunately this attack ends with the murder of an attractive young woman that Neelix had become enamored of. Voyager's Vulcan Security Chief Tuvok goes undercover and finds an illicit memory trade in which the salesman of the resonator coil is a key figure. He determines that B'Elanna's memory was goaded from her in order to be resold, but it was too violent for the illicit Mari tradesmen to contain, and this caused the outbursts among the Mari. Torres is released due to this new evidence, just moments before her brain was to be probed. Nimira herself is shocked to find that all thoughts of violence have not disappeared from her people.
Later at the end of the episode, Seven of Nine urges the Captain not to visit these foreign worlds to avoid such dangerous complications in the future. Janeway, however, turns down her suggestion and remarks that Voyager was built for the purpose of human exploration and that the crew will continue to visit new worlds and take in new experiences since this was part of the ship's mission.
Namira's actress, Gwynyth Walsh was also attracted to the thought-provoking nature of the episode. Shortly after working on the installment, she related, "From my perspective, the episode certainly seemed to be dealing with the censorship issue, which is especially prevalent in the United States right now. The American Far Right [lobby] has a lot of control over what is on television these days, and I think the script attempts to explore the potential negatives of that kind of censorship.
This episode deals with the idea of censorship from a mass perspective. All of society expected to think positively and in a certain fashion. The script serves as an homage to George Orwell and the dystopian Thought Police. The term has come to refer to real or perceived enforcement of ideological correctness, or preemptive policing where a person is apprehended in anticipation of the possibility that they may commit a crime.[original research?]
When Tuvok and Guill conduct a mind-meld to exchange violent thoughts, the dream sequence shows images from another Paramount Pictures production at the time. For a short moment a scene from the film Event Horizon is visible.