Three Klingons — Kor, Koloth, and Kang — come aboard Deep Space Nine. Dax is surprised to see them, as she knew them when she was Curzon Dax. The three have reunited for a final mission and didn't know Dax would be here, but when she learns what their mission is, she insists on being allowed to accompany them.
Years ago, a Klingon criminal known as "the Albino" was raiding Klingon colonies. Kor, Koloth, and Kang, were sent to stop his raids, but the Albino escaped and swore vengeance on their firstborn sons. He made good on this threat, killing all three of their firstborn sons including Kang's son Dax, of whom Curzon Dax was godfather. The four swore a blood oath to kill the Albino someday, but he's always evaded them. Now Kang has found his location and got Kor and Koloth together for an attack.
Trills typically do not remain attached to their past lives, and the Klingons will not hold Jadzia accountable for Curzon's oath, but she still wants to accompany them. With some convincing, they agree. Sisko refuses to grant her a leave of absence, seeing it as Dax wanting to track down and murder a Klingon in the name of a foreign oath she is no longer tied to, but Dax leaves anyway.
En route to the Albino's stronghold, Dax is supicious of Kang's insistence on a frontal assault, and confronts him about his motives. Kang admits that when he came to scout out the system to make sure the Albino was here, the Albino contacted him — tired of the lifelong pursuit, he offered the three an honorable death against his security, and Kang agreed. Dax convinces Kang to fight to win, not to die, and once Kor and Koloth are informed of the truth, they hatch a plan to disable the Albino's security and fight their way in on more favorable odds.
The plan goes off successfully and the four engage the Albino's forces, but Koloth dies in the battle. Kang engages the Albino alone, but his bat'leth breaks and the Albino mortally wounds Kang. As Dax confronts the Albino and hesitates to finish him, Kang stabs the Albino in the back with the remains of his bat'leth, then succumbs to his wounds. Two of the three are dead, but they died in glorious combat, and Kang was able to avenge his son.
Dax returns to DS9 and resumes her duties, but Sisko and Kira give her the cold shoulder on her return.
- Authority Equals Asskicking/Cornered Rattlesnake: The Albino is a Dirty Coward who uses dishonorable tactics and cowers behind his goons, but once his goons are all dead and he's forced to go one-vs-one against Kang, he actually proves to be quite a skilled opponent and actually manages to break Kang's weapon and fatally wound him.
- Badass Boast: When Koloth arrives in Odo's office without being seen.Odo: How did you get in here?Koloth: I am Koloth.Odo: That doesn't answer my question.Koloth: Yes, it does.
- Bittersweet Ending: The mission is a success, and Jadzia is spared from having a murder on her conscience by Kang. But it doesn't matter - once she's back at the station, Kira and Sisko just can't look at her the same way.
Kang: I was right, Dax. Today is a good day to die.Dax: It's never a good day to lose a friend.
- Furthermore, Dax's godson is avenged, but she also loses two of her dearest friends, Koloth and Kang.
- Call-Back: Kang mentions the Klingon restaurant from Melora and Playing God in citing the decline of his culture.
- Continuity Cavalcade: Three of the most prominent Klingons to appear in TOS come back and unite for one last mission.
- Cut His Heart Out with a Spoon: "I will cut his heart out and eat it while he watches me with his dying breath!"
- Deal with the Devil: Invoked word for word in Kang making a deal with the Albino. Appropriate, given what happened in the original episode he starred in the Original Series.
- Dirty Old Man: Kor doesn't mind Dax being an attractive young woman. He really doesn't mind.
- Exact Words: Odo's justification for turning off the holosuite while a drunk Kor is inside, despite Quark's objections. Kor threatened to kill Quark, after all.
- Expy: In creating the characters of the three Klingons as they are now, Kor was inspired by William Shakespeare's Falstaff, while the other two are from The Magnificent Seven (1960) — Koloth after James Coburn's Britt and Kang after Yul Brynner's Chris.
- Faceless Goons: It saves time and money on funny rubber foreheads.
- Famed in Story: When Koloth states that he is a Dahar Master, Odo immediately adopts a respectful tone.
- The Glomp: On seeing Dax is now in the body of a beautiful woman, Kor demands a kiss. He gets a hug instead.
- Going Native: Curzon Dax made a blood oath despite being a Federation ambassador. Far from being just a political move to get the Klingons on side, Dax takes the oath so seriously she continues it as Jadzia Dax.
- Good Old WaysKang: The old Klingon ways are passing. There was a time, when I was a young man, the mere mention of the Klingon Empire made worlds tremble. Now, our warriors are opening restaurants and serving racht to the grandchildren of men I slaughtered in battle.
- Grumpy Old Man: Koloth and Kang.
- He Knows Too Much: Dax worries that the traders Kang spoke to might have warned the Albino. He replies that they'll never warn anyone ever again.
- How the Mighty Have Fallen: Dax reminds Kor of his past triumphs, leading to a rare moment of sobriety.Kor: The only weight I carry now, dear comrade, is my own bulbous body. I was once, if you remember, far less than you see, and far more than I have become.
- I Gave My Word: Interesting variation on this with Dax, as her previous host Curzon gave his word to avenge the death of his godson (Kang's son), also causing unintended Revenge by Proxy.
- It is played with, however. A joined Trill is explicitly not beholden to her predecessor's debts under their tradition, and the Klingons accept this. Kang especially makes it clear that he considers Jadzia Curzon's successor (and essentially his daughter), and thus she isn't bound to Curzon's oath by Klingon standards either. Essentially Dax is still so enraged that Jadzia swears to kill him all over again.
- Irony: Kang dies fighting in a burning house.
- It Works Better with Bullets: Dax works out a Techno Babble means of deactivating the disruptors of the Faceless Goons, so they have to rely on hand weapons.
- Killed Off for Real: Kang and Koloth die of their injuries.
- A Lady on Each Arm: Which leads to a dilemma when you're got a jug of blood wine in front of you.
- Leeroy Jenkins: Kang can't come up with a better strategy than "Attack! Attack! Attack!", prompting Jadzia to peg him as a Death Seeker.
- Legendary in the Sequel: The three Klingon captains Kirk faced are living legends by now.
- Lured into a Trap: The Albino has secretly contacted Kang, offering him a chance for a glorious death in a battle with forty of his mooks. Turns out there was actually a large bomb under the place where this fight is supposed to take place. Fortunately Dax makes Kang tell the truth and comes up with another option.
- Mundane Made Awesome: Koloth is shown cutting his food with exact strokes of his knife, just to show how he's constantly maintaining his skills.
- Mythology Gag: When Kor pulls open the holosuite doors, the sound effect of doors opening from The Original Series can be heard. Fitting, considering Kor was a prominent antagonist back during Kirk's time as captain of the Enterprise.
- Not Too Dead to Save the Day: Kang is fatally wounded in the final confrontation, but he turns out to have enough life left in him to get back up and kill the Albino when Dax is unable to do it, before dying properly.
- Releasing from the Promise: Kang and several others try their best to convince Jadzia that she has no part in Curzon's oath. But she refuses to release herself.
- Retired Badass Roundup: Dax has to work at getting all three Klingon legends to support her joining and to work together for one last glorious battle.
- Revenge Before Reason: According to Trill tradition, Dax has no obligation to anything promised by a past host, in fact Trill society dictates near-total disconnect from past lives, and the Klingons aren't pressuring her either.
- Screw the Rules, I'm Doing What's Right!: Jadzia's way of justifying herself to Sisko.
- Space Pirates: The Albino led a bunch of these before Kor, Koloth, and Kang put a stop to his operation.
- Status Quo Is God: Sisko promises dire consequences for Jadzia and her future in Starfleet should she disobey his orders and go after The Albino. Said consequences never take place.
- Dax was off duty and outside Federation space so there wasn't much he could do to her careerwise. It also helps her case that Jadzia wasn't the one who killed the Albino in the end.
- Dax says it all depends on Sisko whether she can come back. Presumably he never reported her.
- Strike Me Down with All of Your Hatred: With the Albino mocking Dax while her bat'leth is at his throat. Kang mistakes her lack of resolve for her letting him land the death blow himself.
- Sword over Head: Dax balks at killing the Albino. Ironically this is mistaken for Only I Can Kill Him by Kang, who stabs the Albino In the Back while he's mocking Dax's lack of resolve. Kang then thanks Dax for allowing him to strike the death blow.
- Vitriolic Best Buds: Koloth, towards Kor. On seeing him drunk in Odo's holding cell, his immediate response to give up and leave. Even his Famous Last Words are him refusing to die before Kor.
- Wrecked Weapon: Kang has an Oh, Crap! moment when his bat'leth shatters while fighting the Albino.
- Zeerust Canon: Averted; the three actors were horrified to find they'd have to spend hours in make-up being converted to Rubber-Forehead Aliens, as they'd assumed they'd have their Original Series Klingon appearance.
- You Can Keep Him: Koloth goes to bail Kor out of Odo's cells, but is so disgusted by the drunken wretch he walks off and leaves him there. Fortunately Dax overhears Odo complaining about him and convinces Odo to release him into her custody.