DS9 is being buffeted by a plasma storm, so there's only a skeleton crew on board (I.E. they couldn't afford to pay the extras this week.) Odo and O'Brien find Quark practicing yoga on the docking ring. Odo points out the only reason he didn't evacuate was because there wasn't enough room on the shuttle for his wealth. Also, there's some blinky device on the wall which presumably has plot significance, since the camera lingered on it.
Oh, hey, Tim "Tuvok" Russ is in this episode. Dax detects a small incoming vessel caught in the storm and tractor the ship in. The ship turns out to be crewed by Klingons. Yep, there's Tim, as a Klingon. They force Odo to stick himself in a wee box and take him to the infirmary where they force Bashir to stick him in stasis. Then the invaders storm ops, and O'Brien speculates they had Quark's help in disabling the station's security. Indeed, Quark thinks he has a deal with the Klingons, but apparently not.
It turns out the real master mind is... Lex Luthor's dad, who's a Trill. Yay, John Glover! He wants the Dax symbiont. Bashir protests if they remove the symbiont from Jadzia, she'll die. Veral says that he was found unsuitable to accept a symbiont.
While Bashir starts the operation, there's a short-lived attempt in ops to disable the invaders. Bashir extracts the symbiont (which looks like an amorphous grey blob) and sticks it in Veral. Sisko and Kira try to talk Verad's assistant, Mareel (played by Megan Gallagher, who was also Frank Black's wife in Millennuim), but then Verad Dax appears to say hi.
Bashir works to save Jadzia's life, but she's distressed that the symbiont has gone.
Sisko and Dax discuss their pasts, and Sisko suggests that the symbiont return to Jadzia. Verad Dax says if the symbiont is swapped back so soon, it might die. Dax refuses to go to the infirmary and Sisko declares they're no longer friends. Awwwwwww.
Sisko again tries to convince Mareel that Verad has changed. At this point, Quark attacks one of the Klingons. There's something you don't see every day. Quark, of course, loses, and Mareel takes him to the infirmary, though he's quite obviously faking an ear injury. With Quark's help, Bashir renders the Klingon guard unconscious and frees Odo.
Since they can't contact the Klingon in the infirmary, Verad and T'Russ, I mean T'Kar, take Kira as a hostage and head for their ship.
Sisko talks to Mareel, who's having doubts about her relationship with Verad, and talks her into helping him.
Odo ambushes Verad and T'Kar at the airlock, and he and Kira beat up T'Kar while Sisko intercepts and stuns Verad. Verad wakes up in the infirmary, minus Dax. Thus endith teh episode.