Duet begins with Kira and Dax discussing their lives when a ship containing a passenger (Harris Yulin) suffering from Kalla-Nohra syndrome docks at the station. Kira heads down to Doctor Bashir and, seeing the passenger is Cardassian, arrests him on the spot. As it transpires, Kalla-Nohra is only ever found in people who were at a specific work camp during the Occupation of Bajor on the day of a mining accident. Many bad things happened at that camp, so Kira has arrested him as a war criminal.
His claims that he does not have Kalla-Nohra, but instead a similar disease that was mistaken by the transport doctor he was traveling with, are quickly dismissed, and he keeps insisting that he is Aamin Marritza, a military file clerk, who had nothing to do with the crimes committed by the Cardassian occupation. During Kira's questioning of him, a Drunken Bajoran is released from holding muttering about being imprisoned with a Cardie.
While Sisko faces pressure from the Bajoran Government to hand him over for trial, he holds off while he attempts to verify his identity, which is tricky when there are few images of the work camp. During this he discusses the matter with Kira, and his intent to release Marritza if his story checks out. Using a picture from the work camp, the prisoner looks nothing like Marritza but he is a spot on match for Gul Darhe'el, the camp's administrator.
Confronted with this, he admits that he is Gul Darhe'el and gives a long boastful confession about how he slaughtered people and all his other crimes, and how Kira and her Shaakar resistance cell were insignificant. With this it looks like he will be handed over to Bajor for trial and execution, but something's amiss how did he know the name of Kira's Resistance cell?
With this loose thread to sort out, Odo gets in contact with Gul Dukat, who provides surprising information: Gul Darhe'el is dead was given a highly publicized hero's funeral (which Dukat attended). Further investigation reveals that Darhe'el was not even on Bajor on the day of the accident and so could never have contracted Kalla-Nohra and that the prisoner spent a considerable amount of time researching Kira and was taking medication for the aftereffects of surgical alterations. Once again, Kira confronts him with the evidence, claiming that he is Marritza after all trying to pass himself off as Gul Darhe'el, but he tries to cling to it:
- "I am alive! I will always be alive!!! It's Marritza who is dead! Marritza, who was good for nothing but cowering under his bunk and weeping like a woman. Who, every night, covered his ears because he couldn't bear to hear the screaming for mercy of the Bajorans [breaks down sobbing uncontrollably] Covered my ears every night I couldn't bear to hear those horrible screams. You have no idea what it's like to be a coward. To see these horrors and do nothing Marritza's dead. He deserves to be dead.
Marritza finally admits his true identity and his motivations: he believes Cardassia has to face its past and accept responsibility for what it has done, and by having a very public trial he can force Cardassia to deal with it. Despite Marritza's pleas that she help him see his plan through, a moved Kira refuses and releases him.
Kira arranges transport for Marritza to return to his home, saying Cardassia needs good men like him if it's ever to reform. As they head for this transport, the drunken Bajoran from earlier comes up and stabs Marritza in the back. As Kira cradles him as he dies, she looks at the Bajoran.
- Kira: No..... it's not.
The TV screen tends to become unusually blurry at this point, and no amount of whacking seems to fix it
- Accomplice by Inaction:
- Marritza's guilt stems from the fact that he was a witness to the atrocities at the Gallitep labor camp, but was powerless to prevent them.
- By contrast, Kira pushes hard in the beginning for Marritza to be held and punished, even though he was just a desk jockey in the camp who wasn't involved, because she can't bring herself to believe that a Cardassian stationed at Gallitep could possibly be innocent.Kira: As far as I'm concerned, if he was at Gallitep, he is guilty. They're all guilty. His punishment will let Bajor feel some... satisfaction.Dax: It sounds like you're trying too hard to believe what you're saying. You already know if you punish him without reason, it won't mean anything, and you already know vengeance isn't enough.
- Adult Fear: You're a humble file clerk working in the administration of an internment camp where atrocities are being committed daily, before your very eyes, and you're powerless to stop it. Do you stand by and watch, knowing that you have no real ability to prevent these atrocities, and try to live with the guilt as people are massacred daily, or try to stop it, knowing that your efforts will almost certainly fail and the people will be massacred anyway?
- Aesop Amnesia: This episode, unfortunately, started the trend of Kira learning, then forgetting, then learning again that no single people, particularly the Cardassians, is completely evil (or good).
- All for Nothing: After all Marritza's planning, he's eventually found out through Odo's detective work and Bashir's medical diagnosis. And just when Marritza and Kira are about to turn a negative into a positive, he gets murdered.
- Artistic License Medicine: Marritza is stabbed in the lower back by a small knife and dies instantly. They're practically nearby sickbay when this happens and Kira makes no attempt to call for Bashir or carry him there, while it's been established that Trek medicine can treat the freshly deceased. Remember too that Picard was stabbed through the heart and lived to laugh about it, so the whole ending feels rather rushed. Perhaps Cardassian biology explains this or the knife itself contained a lethal poison, but they don't actually say that.
- Ask a Stupid Question...: Kira asked Marritza what a file clerk was teaching at a Cardassian military academy.Marritza: Believe it or not, filing.
- The Atoner: Marritza.
- Batman Gambit: Marritza's plan to be captured, tried, and executed, to force Cardassia to admit its atrocities. He surgically alters his face to that of a known war criminal and deliberately books passage to Deep Space 9 after putting his affairs in order. He at first tells the truth about his identity but lies about a medical condition, knowing it will lead to an investigation and a picture of Gul Darhe'el, who he resembles. The gambit only fails at the end because Odo notices that the situation is too perfect.
- Bottle Episode: The episode, which needed only one guest star and used entirely existing sets and costumes, cost less than half of the usual budget and is considered one of the finest episodes of the series.
- Boring, but Practical: Marritza's position of filing clerk is an unglamorous but useful position. It also helped give him access to the files he needed to provoke Kira in order to face charges.
- The Butcher: Of Gallitep.
- But for Me, It Was Tuesday: Invoked by Marritza while pretending to be Gul Darhe'el.Darhe'el!Marritza: What you call genocide, I call a day's work.
- ...But He Sounds Handsome: As Gul Darhe'el, Marritza compliments his own filing system.
- And before he's "revealed" to be Darhe'el, Marritza praises the man's leadership.
- Call-Back: Marritza suggests that his sem'hal stew could use a bit of yamok sauce. Too bad Jake and Nog traded it all for self-sealing stem bolts four episodes ago.
- Cerebus Syndrome: After crew members spouting gibberish, surreal tabletop games and Rumpelstiltskin for some reason, this is the episode where Deep Space Nine gets very, very serious about its premise.Kira: Commander, if you'd been there twelve years ago when we liberated that camp, if you'd seen the things I saw. All those Bajoran bodies starved, brutalized. Do you know what Cardassian policy was?! Oh, I'm not even talking about the murder; murder was just the end of the fun for them! First came the humiliation! Mothers raped in front of their children, husbands beaten till their wives couldn't recognize them, old people buried alive because they couldn't work anymore!
- Chewing the Scenery: Marritza does this when impersonating Darhe'el. He deliberately invokes the Evil Is Hammy trope in-universe because he wants to be tried and executed.
- Cruel Twist Ending: This could be the cruelest Star Trek ending since "The City On The Edge Of Forever." All Marritza's meticulous planning and showy performances, then his chance at redemption by another means after Kira learns the truth, only to be unceremoniously murdered in cold blood by a drunken lunatic, right in the middle of the promenade.
- Dead Person Impersonation: Gul Darhe'el's death was a matter of public record on Cardassia, which is what eventually blows Marritza's cover when Odo gets access to those records.
- Deadpan Snarker:Dukat: I do miss working with you, Odo. I miss our games of kalevian montar.Odo: As I recall, Gul Dukat, we played one game and you cheated.
- Death Seeker: Marritza, who impersonates Darhe'el in the hopes of being tried and executed, motivated by his guilt over what he witnessed during the Cardassian Occupation.
- Didn't Think This Through: Marritza's plan would have worked but for the fact Cardassia considered Darhe'el a hero and buried him at a state funeral. His plan only would have worked if the Cardassian had been living in shame.
- Early Installment Weirdness: Gul Dukat refers to the "Cardassian Empire." Later references established it as the Cardassian Union.
- Enhance Button: Played straight, but lampshaded. When they first try it the computer takes a minute to process, causing the image to look like a real photo enlargement before the magic enhancement kicks in. Sisko complains that he needs better than that.
- Evil Is Hammy: Marritza seems to be fully aware of this, as he really starts hamming it up when he's trying to get Kira to believe he's Darhe'el.
- I Did What I Had to Do: Kira's rationale for having killed Cardassian civilians. Marritza also quotes this trope almost verbatim while impersonating Darhe'el.
- Jerkass Façade: Marritza, and he makes a hell of a show of it for a while, till he just can't anymore.
- Karma Houdini: Gul Darhe'el died peacefully, received a state funeral with full Cardassian military honors, and didn't even have the good grace to contract Kalla-Nohra syndrome like most of the camp's inhabitants.
- Motivational Lie: Marritza lied about his identity and running the work camps, to motivate Kira to put him on trial.
- Multilayer Façade: Marritza is impersonating Gul Darhe'el impersonating Marritza.
- A Nazi by Any Other Name: Marritza's stories of the work camp are clearly meant to invoke Auschwitz, with the Cardassians being analogous to Nazis, and the Bajorans to Jews and other minorities put in concentration camps.
- To a lesser extent, the mealy-mouthed war crime denials Sisko puts up with call to mind Imperial Japan's own tendency to deflect accusations of its atrocities. Additionally, the fact that the real Gul Darhe'el was buried with full military honors at one of Cardassia's greatest memorial sites seems to call to mind the Yasukuni Shrine Controversy.
- "The Reason You Suck" Speech: Delivered twice by Marritza, once pretending to be Darhe'el as he tries to enrage Kira into sending him to Bajor to be executed, the second berating himself for his cowardice as a filing clerk at Gallitep.
- Red Baron: Gul Darhe'el, a.k.a. "The Butcher of Gallitep".
- Reports of My Death Were Greatly Exaggerated: Once Kira mentions Darhe'el has been dead for several years, Marritza tries to invoke this trope in rebuttal.
- Sarcastic Confession: Marritza actually admits to being a file clerk at Gallitep in his first interrogation, but rolls with it when he's "outed" as Gul Darhe'el.
- Screw the Rules, I'm Doing What's Right!: Kira, as usual. She claims that arresting Marritza as a war criminal is the right thing to do, even if there's no legal justification.
- Similarly, when Marritza reveals his true character, Kira releases him from the cell, no longer caring whether or not Bajor would still want to prosecute him.
- Shell-Shocked Veteran: "Darhe'el" couldn't bear to hear the screams of the Bajorans his superiors murdered, and his experiences at the labor camp have shaken him to his core.
- Shout-Out: To The Man in the Glass Booth, which inspired the plot.
- Spotting the Thread: The first clue that Darhe'el is not who he says he is comes when he mentions the name of Kira's former resistance cell. Kira doesn't think anything of it at first, but Odo finds it incredibly suspicious that Darhe'el, whose duties did not involve fighting the resistance, would know (let alone remember) such a specific piece of trivia (because Darhe'el is actually right - individual cells, even the Shakaar cell, were basically fleas to the Cardassian military, and the withdrawal was due more to overall political pressure than anything). He claims to have seen her name in reports he read in his spare time, which Kira probably would have bought, but by then more evidence was appearing that unraveled the thread even more.
- Swiss Cheese Security: Odo is usually on the ball, but failing to catch Marritza's murderer in time is a serious faux pas on his part.
- That Man Is Dead: Marritza thinks this of himself.
- Too Dumb to Live: Discussed by Odo and Dukat over the comm, why would an innocent old man head to a Bajoran space station and pretend to be an infamous Cardassian war criminal, an act guaranteed to get him captured and executed? Turns out, there's a method to his apparent madness...
- Villainous Breakdown: This is inverted, as Marritza's breakdown is when he starts talking about himself (still pretending he's Darhe'el), and how he would spend nights trying to cover his ears from the screams of suffering people, and that's what causes him to burst into tears and finally break his facade.
- You're Insane!: Said by Kira once "Darhe'el" stops denying and starts bragging about his war crimes. Which is almost certainly exactly the reaction that Marritza wanted.
- Zero-Approval Gambit: Marritza's plan was to, essentially, act as unlikable and evil as possible in order to get put on trial and expose Cardassia's war crimes to the galaxy.