Blood Oath: Three old Klingons arrive on the station to fulfill a blood oath they make years earlier.
Man, the Trek never ends.
Quark bitches to Odo about a Klingon who's bogarting the holodeck. Odo tells him to shut the power off and sadly prevents the resulting enraged Klingon from throttling Quark. Sad Klingon is Kor, from the TOS episode "Errand of Mercy". Koloth (from "The Trouble with Tribbles") turns up to bail him out, but is disgusted by his fellow Klingon's behavior.
Dax is excited by the news that her old Klingon pals are on board the station, and gets Odo to let Kor out. Finally Kang (from "Day of the Dove") turns up and announces he's found the Albino.
Dax tells Kira about how the Albino killed the firstborn of each of the three Klingon captains, one of which was Kurzon Dax's godson. She's wracked with indecision over whether to help them take revenge.
Kor's a bit sad because he's not as svelte as he used to be. Dax gives him a bit of a pep talk, and then goes to watch Koloth wave a Bat'leth about in a holosuite. When he scoffs at her fighting ability, she fights him. And pretty much loses, but he says she can come anyway. Kang still says she can't though. Dax takes him aside for a talk and he begrudgingly agrees to let her tag along.
Sisko tries to talk her out of going, but fails. Dax and her three Klingon pals set off to assault the Albino's compound. On the way, they argue over which tactic to use, and Dax realises that their real objective is to die in battle, the Klingon way. Kang reveals that he organised with the Albino to fight to the death. Dax says she has a plan to disable the weapons of the Albino's guards.
So, the Klingons storm the compound and start killing guards. Koloth is killed, and the Albino stabs Kang. While Dax has the Albino at bat'leth-point, Kang stabs the bugger in the back and then promptly dies himself. Dax returns to DS9 so Sisko can glare at her.