With the morphogenic plague ravaging Odo, Bashir is left troubled over the fact that the Federation could sanction Section 31 to create and use a biogenic weapon with the purpose of committing outright genocide against the Founders; even if they are at war, that the Federation would allow this to happen under their watch is a bitter pill for the good doctor to swallow. Both Bashir and O'Brien view Section 31 as a great evil that could not be suffered to continue for the sake of the Federation, and with its director Sloan willing to go to any lengths to complete his task, Bashir has decided the only way to best him and get the cure for Odo is to play his game. To that end, with Captain Sisko's blessing, Bashir sends out a fake report claiming that he found a cure for the morphogenic virus to lure out Sloan.
Sloan takes the bait, intruding upon Bashir's quarters at night with a mission to give him. This time, however, Bashir is ready for him; he erects a containment field around Sloan, and tells him that he needs a cure for Odo. Sloan feigns ignorance about a cure, but Bashir was prepared for the possibility that Sloan would not be willing to cooperate. Sloan warns Bashir that turning him over to Starfleet Security would prove fruitless, but unfortunately for him, Bashir has no such intentions; he lowers the field for a second to stun Sloan with his phaser, then takes him to sickbay and restrains him with a force field. Bashir knew that Sloan knew about the cure; otherwise, he would never have come to the station to try and lure Bashir away while he destroyed it. Since Sloan would never give up the cure willingly, Bashir was prepared to use rather underhanded means; with O'Brien's help, he would use illegal Romulan mind probes to get the information he needed.
Realizing that he underestimated Bashir, Sloan activates a neuro-depolarizing implant in his brain, killing himself instantly. Bashir manages to stabilize his vitals, but it is only a temporary measure; higher brain functions would cease within an hour. There is only one way to get the cure now; using a multitronic engrammatic interpreter to link his mind directly with Sloan's, allowing him to probe his memories directly. This was an incredibly dangerous proposition, however; Sloan's memory pathways would be scrambled as a result of his suicide implant, and if Bashir was still linked to Sloan's mind when his brain functions ceased, he would die as well. O'Brien insists on accompanying Bashir, with Bashir assuring O'Brien that once they are ready to leave, he can raise his own blood pressure at will to trigger the interpreter's failsafe, disconnecting himself so he can disconnect O'Brien as well.
When the two enter Sloan's mind, they find themselves in a turbolift on Deep Space 9, where they are greeted by Sloan. This rendition of Sloan appears cooperative and wishes to give the cure to Bashir, but when he tries to explain how the cure works, the dominant Sloan's mind prevents him from doing so until they attend a reception, where Sloan apologizes for all the harm he had done in his life and says fond farewells to his friends, family, and colleagues. Just as Sloan is about to give a datapad to Bashir with the cure, however, he is shot and killed by another Sloan, who Bashir and O'Brien chase through the halls of Sloan's mind, only for them to be shot and wounded by a guard.
As they laid in the corridor, exhausted, Bashir realizes that he can't increase his blood pressure, leaving them trapped in Sloan's mind. He and O'Brien have a heart-to-heart where Bashir confesses that he loves Ezri Dax, and that he had a sneaking suspicion that even though O'Brien loved his wife, he preferred Bashir's company. When they see "the light" coming from behind them in the corridor, they get to their feet and prepare to open a door that could lead to the cure, only for Bashir to awaken when Sisko removes the interpreter from his head. Sisko had pulled them out because Sloan's condition was rapidly deteriorating. Bashir tries to stabilize Sloan, but it is no use; he dies on the table.
Devestated, Bashir retires to his room to read Jadzia's copy of A Tale of Two Cities, only to notice something peculiar; the opening line of the story appeared in the middle of the book. This could only mean one thing, as he explains to O'Brien: they are still inside Sloan's mind, with Sloan's subconsciousness trying to trick them into keeping their minds linked long enough for him to die, so Bashir and O'Brien can die with him. The door they were about to open before being tricked into thinking they had awakened must be the one that leads to the cure!
Through the door, Bashir and O'Brien find Sloan in an office with datapads strewn about. Sloan explains that everything about Section 31 is contained in this room, with Bashir amazed to find more than enough information to expose the organization and bring it down. O'Brien, however, warns Bashir that this is another trick; Sloan is trying to distract him and keep their minds linked as he dies. O'Brien finds the pad with information relating to the cure, and gives it to Bashir before convincing him to wake up.
Bashir increases his own blood pressure and triggers the interpreter's failsafe, this time awakening for real, with Sisko and Ezri nearby. After awakening O'Brien, Bashir sets to work using the knowledge he took from Sloan, now completely dead, to synthesize a cure and give it to Odo, who is instantly cured of the virus. O'Brien and Bashir then share a toast at Quark's, with Bashir thankful to O'Brien for saving him from Sloan's attempt to bait him.
Tropes in this episode:
- And Now For Something Completely Different: This episode focuses on a single storyline, as opposed to switching between several threads.
- Batman Gambit: Bashir has a forcefield Booby Trap waiting, know that Sloan will do his Trespassing to Talk intro. When Sloan claims not to know the cure, Bashir points out that he'd need to know what he was looking for while searching Bashir's files. Just blowing up his Sickbay would be too unsubtle and uncertain.
- Battle in the Center of the Mind: More of a game of cat-and-mouse than a battle, but same idea.
- Big "WHAT?!": Sisko's reaction to Bashir's theory that Section 31 infected Odo with the changeling virus, followed by a Face Palm as Bashir explains The Plan.
- Bottle Episode: It helps that everything in Sloan's mind looks like either DS9 or the Defiant.
- Chekhov's Gun: Bashir mentions reading A Tale of Two Cities early in the episode. When he returns to it later on and discovers the opening line midway through the book, he realizes all is not as it seems.
- Famous Last Words: Sloan, before activating his neural depolarizer."I misread you. I thought you were just a misguided idealist, but you're a dangerous man. People like you would destroy the Federation if given the chance. Fortunately, there are people like me...who will die to protect it."
- Foreshadowing: In the after-hours bar, O'Brien reminds Bashir that they have to focus on the cure for Odo while Julian is growling his desire to rip out Section 31 by the root. In the climax, O'Brien is the one who pulls them out of Sloan's mind when Julian would have stayed to gather the evidence he needed to bring it down.
- A Glitch in the Matrix: Bashir finds the novel he is reading starting over again because he never read it before and doesn't know where it goes from there.
- Go into the Light: Defied—when Bashir and Julian see the Light in Sloan's mind, O'Brien refuses to simply surrender to it.
- Hard-Work Montage: O'Brien setting up the gizmos to link himself and Bashir with Sloan.
- How Dare You Die on Me!: Bashir refuses to let Sloan die before revealing the cure.
- Journey to the Center of the Mind: A very twisted mind at that.
- Lured into a Trap: Sloan. Even he can barely believe it.
- Mind Rape: Bashir intends to do this to Sloan using Romulan mind probes to get the cure to the changeling plague, willing or otherwise. Sloan triggers his Suicide Pill neural implant to thwart this, but Bashir manages to keep him clinically alive long enough to get the information.
- Nerves of Steel: Even after getting captured, Sloan remains calm and snarky, only getting nervous when Bashir pulls out the Romulan mind probes.
- Not So Different: Bashir is using an illegal and quite sinister method in order to do what he believes is right. Sloan was on to something when he wanted to recruit him for Section 31... But now, he calls Bashir a "dangerous man" instead - which, from Bashir's perspective, would certainly apply to Sloan himself.
- Oh, Crap!: Sloan becomes quite visibly disturbed when Bashir states his intention to use Romulan mind probes to find the cure.
- The Oner: One of the longest shots in all of Star Trek; when Bashir and O'Brien are trapped in Sloan's mind and believe themselves doomed, they have a conversation about how much they "like" eachother; this entire conversation is held in one shot that runs just shy of three minutes in length.
- Other Me Annoys Me: A bizarre variation: just as Sloan is about to give Bashir the cure for Odo — the part of himself who is repentant for the horrors he did, for the things he had to sacrifice in what he now sees as a wasted life — another Sloan, the unfettered part of himself, shoots him.
- Out-Gambitted: Sloan finally gets out-played because he knew he might entice Bashir to stay too long and be taken with him in his final minutes in life, but O'Brien's dedication to the purpose of the mission is what shakes Bashir from his desire to learn more about Section 31.
- Percussive Therapy: Julian sneaks into the bar after-hours to throw darts really hard.
- Riddle for the Ages: Did Section 31 actually infect the Founders? They certainly didn't want anybody to find a cure, but it isn't explicitly determined if they were responsible.
- Shame If Something Happened: Sloan tries to pull this regarding O'Brien's family, but Bashir tells him to shut up.
- Snipe Hunt: Sloan appears with another mission for Bashir, designed to get him off the station while Sloan finds the cure. Bashir has other ideas.
- Stealth Pun: The part of Sloan's mind that refuses to give up the cure looks like the Defiant.
- Suicide Pill: A neural implant, but still.
- Taking You with Me: Sloan attempts this on Bashir and O'Brien. Fortunately, The Power of Friendship wins out.
- Techno Babble: O'Brien of all people is confused by Bashir's explanation of the neural whatever link.
- This Is Gonna Suck: A variation—when Bashir tells Sisko that his plan involves using illegal Romulan mind probes on Sloan, the look on Sisko's face and his little "Oh" both say, "This is gonna be one of those plans."
- Trespassing to Talk: Sloan does this to Bashir—just like Bashir was expecting.
- Unperson: The good part of Sloan remarks that he is a version of this. Having wiped away all traces of his life beforehand, leaving no footprints to follow, he won't be missed because he isn't even remembered.
- Xeno Nucleic Acid: The cure for the Changeling virus uses adenine, radodine, lidestolinine, and asporanine.
- Your Mind Makes It Real: Getting shot in Sloan's mind makes Bashir and O'Brien feel like they've really been shot.