The Most Underrated Episodes Of Star Trek: Deep Space Nine

"Deep Space Nine" has become known for strong recurring characters like Starfleet security officer Michael Eddington, introduced in Season 3 as a potential rival for Odo. The onset of the Dominion War likely led some fans to suspect he was actually a changeling infiltrator, but "For the Cause" proved that theory wrong.

In this episode, Eddington and Odo believe that a Maquis agent is planning to hijack a shipment of valuable technology headed for war-torn Cardassia, and they suspect that it may be Sisko's new girlfriend Kasidy Yates. Sisko reluctantly agrees to let them monitor her activities, but it's soon revealed that she was only a distraction. Eddington himself is the Maquis operative, and this reveal kicks off a subplot that sees Sisko obsessed with hunting him down for betraying Starfleet.

Though episodes like "In the Pale Moonlight" became the show's most highly rated for dealing with moral complexities, "For the Cause" did it nearly as well, a thrilling story with plenty of twists and turns. It raises interesting questions in light of Sisko's later actions in the series, and Eddington's behavior ignites a lively debate on the morality of war.

The addition of Worf to the series in Season 4 meant plenty of stellar Klingon episodes through the rest of the show's run. Several such episodes went on to become fan favorites, but the show's finest Klingon-centric episode may in fact be the pre-Worf "Blood Oath." It's an exciting story of revenge that unexpectedly brings back three Klingon characters not seen in live action since the original "Star Trek" series.

The episode sees Kang from "The Day of the Dove," Kor from "Errand of Mercy," and Koloth from "The Trouble with Tribbles" reuniting — in updated make-up — for a quest to hunt an old rival. Decades before, a villain called the Albino killed each of their first born sons and they swore a blood oath to one day get revenge. All three arrive on "Deep Space Nine" to find Curzon because they have finally located the Albino. But, with Jadzia now the host to the Dax symbiont, they are uncertain if she should be allowed to join their quest.

The surprise return of Kang, Kor, and Koloth proved not just crowd-pleasing, but rewarding too, giving new insight into Dax's past. Kor returned several more times in the series, later joining Worf and Dax on another quest in "The Sword of Kahless."

More humorous "Deep Space Nine" episodes are centered on the station's resident Ferengi, bar owner Quark. The beloved installment "Little Green Men" is among the show's very best, but there's another Quark-centered story that gets little love. That's probably because the underrated "Business As Usual" is a surprisingly serious story, one that sends Quark into a moral crisis.

On the verge of financial ruin, Quark receives an offer from his cousin Gaila that he can't refuse: Join him in his business as an arms dealer. The job offers him fantastic riches, but loses him the friendship of his closest friends on the station. At first, he's thrilled to be raking in the latinum, but he soon has second thoughts when a client turns out to be a tyrant looking to wipe out millions of lives. His new benefactor, the charismatic but dangerous Hagath, won't let him quit, and he fears he may have to lose his life if he wants to keep his conscience.

With some of the series' best guest performances, the episode puts Quark through the wringer and once and for all proves that he's not the morally bankrupt con artist he is often portrayed as.

The everyman of "Star Trek," O'Brien went from stalwart crew member on "The Next Generation" to the writer's favorite punching bag on "Deep Space Nine" thanks to his lovable, sympathetic demeanor. O'Brien gets raked over the coals in some of the series' best episodes, like "Hard Time," "The Visionary," and "The Assignment." But one of the most underrated O'Brien episodes that saw him tortured and abused is Season 2's "Tribunal."

A sequel of sorts to the "TNG" episode "The Wounded," this episode further explores O'Brien's time fighting in the Cardassian Wars and his bias against the antagonistic alien race. It begins when he meets an old fellow soldier from his time in the war, Raymond Boone, just before leaving the station for a vacation with his wife Keiko. While on their way, O'Brien is scooped up by a Cardassian warship and accused of plotting a deadly bombing. When Sisko and the crew realize that the Cardassians are planning an elaborate show trial, Odo discovers that there's more to the allegations than meets the eye.

This is one of the finest and most underrated trial episodes in "Star Trek" history. With a memorable guest appearance from TV legend Fritz Weaver and powerful performances from René Auberjonois and Rosalind Chao, "Tribunal" is an effective political thriller that cuts deep.

The Season 3 premiere "The Search" is one of the best "Deep Space Nine" episodes according to IMDb, but that season's finale, "The Adversary" might be even better. The third year of the show saw some dramatic escalations as the Dominion became a major threat, and it all came to a head in the Season 3 capper. Though not the kind of true cliffhanger that "Star Trek" fans had grown used to on "The Next Generation," it closed out the year on a terrifying note, with a dark portent of things to come.

A classic submarine thriller in the finest "Star Trek" tradition, it begins with Sisko taking the Defiant on a mission to the Federation border with the Tzenkethi. An unknown saboteur locks the crew out of the ship's systems and sends the Defiant barreling into enemy territory. While looking for answers, the crew discovers there's a Dominion infiltrator aboard the ship, a shape-shifter disguised as one of them. Now they must uncover the enemy agent and regain control of the ship before they cross into Tzenkethi space.

Odo finds himself in a life or death struggle with one of his own kind in this episode. The stakes are high — no matter what happens, the Federation is looking at an all-out war, either with the Tzenkethi or the Dominion. "The Adversary" is both an important episode and one of the most underrated.

Perhaps the most underrated "Deep Space Nine" episode, nobody ever talks about "Field of Fire." With nail-biting suspense and pulse-pounding plot twists, it's an edge-of-your-seat crime drama the likes of which "Star Trek" has rarely seen. This psychological thriller is a sequel of sorts to Season 2's "Equilibrium," the episode that introduced Juran, a past host of the Dax symbiont.

"Field of Fire" opens with the shocking murder of a young Starfleet officer after a night out celebrating his transfer to Deep Space Nine. During the initial examination of the murder scene it's discovered that the victim was killed not with a phaser, but with a primitive projectile weapon. Having been the last person to see the young man alive, Ezri becomes obsessed with finding the person responsible. To do so, she'll need the help of Juran Dax, a dangerous homicidal killer who has been buried in her psyche for decades. But, while Juran offers valuable insight that helps her track down the murderer, he also brings her perilously close to becoming a killer herself.

Joining the show in its final season, Ezri Dax only got a year on "DS9." "Field of Fire" is her finest hour: Not only is it a brilliant mystery, but, with the normally nervous Ezri finding a way to connect with Juran, it proves that she is just as capable as any of her previous hosts.

The Season 3 episode "Second Skin" is a favorite of fans who love Major Kira Nerys. It sees enemy agents attempting to convince her that she's actually the daughter of a prominent Cardassian politician named Tekeny Ghemor, and that her entire life as a Bajoran is a lie. In the end, it was all revealed to be a ruse to expose Ghemor's allegiance to a group of dissidents. In "Ties of Blood and Water," we learn that Kira and Ghemor have stayed in touch, with the Major seeing the elder Cardassian as a father figure.

Arriving on the station, Ghemor reveals that he is dying, and — in accordance with Cardassian tradition — he must spend his final days revealing his life's secrets to those closest to him. He chooses to bear his soul to Kira, who initially views it as a military debriefing. But, as Ghemor begins to open up, it becomes much more than that. Meanwhile, Dukat and the Dominion plot to have Ghemor assassinated, fearing what damage his secrets could do. When Kira discovers that Ghemor was responsible for a horrific atrocity during the Bajoran Occupation, she realizes that he might not be the man she thought he was.

One of the most powerful arcs in "Deep Space Nine" was Major Kira moving past her hatred of Cardassians. "Ties of Blood and Water," though overlooked by many, remains an important part of that story, an episode that illustrates the power of forgiveness.