Dr. Bashir finds Chief O'Brien to be a less conversational lunching companion than Garak, who is still missing with Odo as the two investigate the bombing of Garak's tailor shop. Julian misses his friend and O'Brien is confident they have not been destroyed because debris from their runabout hasn't been found.
O'Brien is called to Ops where tetryon emissions precede the decloaking of the Cardassian-Romulan fleet. They ignore Deep Space Nine's hails and proceed through the Wormhole to the Gamma Quadrant. The Cardassian Obsidian Order has formed an alliance with the Romulan Tal Shiar, and they are on their way to attack the Dominion.
On the lead ship of the Cardassian-Romulan fleet, Enabran Tain and Garak reflect upon their times together in the Obsidian Order, the Cardassian secret police. Garak says that he intends to 'look up' a number of people once he returns to Cardassia Prime, including Gul Dukat. Tain feels that Garak will be able to "eliminate" anyone after the current mission is completed. Romulan Colonel Lovok is introduced to Garak and is immediately suspicious of him. Lovok informs them that the fleet has recloaked and are setting course to the Founders' homeworld, an important center of Dominion operations, at Warp 6. Any faster could make them detectable through their cloak by the Jem'Hadar.. Tain tells Garak that his first assignment is to extract all information that is possible from Odo who is being held in quarters surrounded by a force field.
Back at DS9 the senior staff, including security chief Michael Eddington, are shown an intercepted video where Tain lays out his plans to destroy the Dominion. Neither the Romulan or Cardassian governments are eager to try to stop the attack on the Founders by these rogue forces. After all, if they should beat the odds and succeed in bringing the Dominion down, all the races of the Alpha Quadrant would be safer for it. Starfleet is not planning to intervene either. Vice Admiral Toddman explicitly instructs Commander Sisko to keep the Defiant guarding Bajor. Directly after this meeting Sisko instructs the senior staff that as a 'volunteer mission' he is going to go to the Gamma Quadrant with the Defiant to rescue Odo.
Pressure is again put on Garak to extract information from Odo about the Founders and their planetary defenses. The Obsidian Order has developed a device that emits a quantum stasis field which should inhibit Odo's shapeshifting ability. Garak does not seem pleased with this news and Tain suggests the Tal Shiar should continue the interrogation. Garak is visibly upset and insists that Odo is his prisoner and that it is his duty to question Odo further.
Inexplicably the Defiant loses cloak. Security Chief Eddington admits that he has sabotaged the cloaking device under direct order by Admiral Toddman. Despite Sisko's noticeable frustration with Eddington's betrayal, Eddington requests to continue his duties in the current mission. Further, he gives his "word" that he will not again betray him. Sisko immediately observes that it is his policy to not question the "word" of a Starfleet officer, and he grants Eddington's request. Sisko gives Chief O'Brien a two hour deadline to fix the cloak, which he meets.
Garak begins questioning Odo and using the quantum stasis device. Odo is about ready to return to liquid state and is discomforted at being forced to maintain humanoid form. As time passes, Odo begins to lose cohesion and taunts Garak. It is clearly bothering Garak to see Odo in pain and he encourages Odo to confess anything - even to lie - as long as he gives up some information. Odo admits his deep-seated desire to return to the Great Link which is information Odo hadn't shared with Starfleet, allowing Garak to deactivate the device and end the interrogation.
As the Cardassian-Romulan fleet arrives at the Founders' homeworld, Tain quips "So much for the Dominion, open fire!". They are initially pleased with the damage they are doing to the planet but Garak quickly discerns that the Founders are using an automated transponder to send back false life sensor readings from the planet. Suddenly 150 Jem'Hadar ships emerge from the Omarion Nebula and engage the fleet. "The Battle of the Omarion Nebula" annihilates the fleet and is later compared by Admiral Toddman to the Battle of Wolf 359, the spectacular crushing of Starfleet by the Borg some four years earlier.
During the battle, contact is lost with engineering aboard Tain's warbird. Lovok goes to investigate, leaving Tain in command of the bridge. Garak, seeing the battle not going so well, makes his way off the bridge to locate and save Odo. They run into Lovok, weapon drawn, who reveals himself to be a changeling. Lovok confesses that the Founders viewed the Tal Shiar and Obsidian Order as threats and helped push this plan forward in order to destroy them. As far as the Founders are concerned only the Klingon Empire and United Federation of Planets remain as threats. Odo is again presented with the choice of joining the Great Link which he declines.
Garak makes his way back to the bridge in an attempt to save Tain, but he refuses to leave. Tain feels that he has become old and let his pride override his instinct. Odo has to knock Garak out to force him onto the runabout and escape. They are pursued by the Jem'Hadar and they lose shields. When all seems lost Garak sincerely apologizes and Odo accepts the apology, saying that he understands Garak's desire to return home. The Defiant decloaks and is able to transport Odo and Garak onboard. Since the battle is underway the Defiant is able to slip away (mostly) unnoticed and make it back to the wormhole.
Sisko is forgiven for disobeying a direct order and Garak begins to clean up the mess in his shop. Even though Odo doesn't eat food he suggests that he and Garak dine together occasionally.