Necessary Evil (Star Trek: Deep Space Nine)

A Bajoran woman, Vaatrick Pallra, hires Quark to retrieve a strongbox from her late husband's shop on Deep Space Nine. Quark opens it to find a list of Bajoran names. A stranger, Trazko, sneaks up, shoots Quark and steals the list. As Dr. Bashir tries to revive Quark, Rom tells Odo about the list of names, and that the box was hidden in the shop during the Cardassian Occupation.

In a flashback, five years earlier, Odo is solicited by Gul Dukat to investigate a murder on behalf of the Cardassian regime. Odo interrogates Vaatrick Pallra, the deceased's widow. She claims her husband had been having an affair with Kira Nerys. When he interviews Kira, she says that there was no intimate relationship between her and Vaatrick, and that she was interviewing for a job at Quark's at the time of the murder.

In the present, Rom tells Odo that one name on the list resembled "Ches'so". Odo interviews Pallra, who claims ignorance of the list of names and the name "Ches'so". She also refuses to divulge who loaned her the money to pay her past-due electricity bill. Kira identifies "Ches'so": a philanthropist named "Ches'sarro", who has just died.

Five years earlier, Quark admits that Kira bribed him to provide a false alibi. When Odo confronts her about it, Kira reveals that she was committing a terrorist attack on the station. Odo tells Dukat that Kira is not the culprit in the murder.

In the present, Odo deduces that the names on the list are Bajorans who collaborated during the occupation, whom Pallra has been blackmailing. At the infirmary, Trazko attempts again to kill Quark; Rom saves Quark's life by screaming, gaining the attention of security forces. Brought to DS9, Pallra denies knowing Trazko, but Odo has confirmed that she had transferred a large sum of money into his bank account. When she declares her innocence in the murder of her husband, Odo replies, "I know."

Odo has realized that it is Kira who killed Vaatrick five years earlier. He tells Kira that he began to suspect her when she was able to identify Ches'saro so quickly. When he deduced that the list consisted of Bajoran collaborators, Odo realized that Vaatrick was a collaborator too, and now understands that Dukat chose him to investigate so as to keep distance from his collaborators. Kira, a member of the resistance, killed Vaatrick when he discovered her trying to steal the list of names. She never told Odo because she was afraid it would affect their friendship. Kira asks him if he will be able to trust her again, and he is unable to answer.

In 2016, The Hollywood Reporter ranked "Necessary Evil" the 19th best episode in Star Trek: Deep Space Nine.[2] They note this as an episode that differentiated this series from its predecessor, Star Trek: The Next Generation, and place the episode in the murder mystery genre.[3]

In 2017, ScreenRant ranked this episode the 11th darkest episode of the Star Trek franchise.[4]

In 2018, SyFy recommend this episode for its abbreviated watch guide for the Bajoran character Kira Nerys, noting that the episode explores the character's past during the Cardassian occupation.[5] In the episode, an attack on Quark leads to deep trek into the past of the character Kira and Odo, and the dark days of the Cardassian occupation.[6]

In 2019, Tor.com noted this as an "essential" for the character of Odo, remarking that helps establish the character and what it was like for him when he worked for the Cardassians.[7] In the show's back story, the Deep Space Nine space station was previously operated by the Cardassian aliens of the Star Trek franchise.[7]

• Star Trek: Deep Space Nine DVD set, volume 2, disc 2, selection 4.
• P. Farrand, Nitpicker's Guide for Deep Space Nine Trekkers New York: Dell (1996): 117 - 120

Wikiquote has quotations related to: Necessary Evil

• "Necessary Evil" at IMDb
• "Necessary Evil" at TV.com

• Necessary Evil at Memory Alpha (a Star Trek wiki)

• Necessary Evil at StarTrek.com