T'Pol is reading at night, when she's contacted by the Vulcan High Command. All they say is that they've found a guy called Menos, who is three days away. The next morning, she tells Archer that he will receive a transmission from Admiral Forrest regarding a secret mission. Archer is annoyed at the idea of being "used" by Vulcans again, but is also somewhat amused by the situation. Archer and T'Pol tell the others via a staff meeting, and Trip is grumpy about not knowing what's going on, but Malcolm decides to use the time to re-calibrate the torpedo launchers. Travis volunteers to be T'Pol's pilot.
That night, she asks Archer to accompany her on the mission and explains what's going on — a surgically-altered Vulcan fugitive named Menos is at large, and two years ago, T'Pol, who was part of the Ministry of Security, tried to catch him but couldn't, and she's now assigned to try again. Archer, while still annoyed, accepts, being glad that T'Pol trusts him.
Trip wants to know what's going on, but Archer doesn't specify beyond helping T'Pol with her "unfinished business" and leaves him in command. On the way, T'Pol explains to Archer that Menos's crime was smuggling biotoxins used for making weapons. They land on a moon and go to a bar, where T'Pol confirms that Menos is hiding.
Travis guides the door, while Archer and T'Pol search for Menos. T'Pol almost finds him, but then an angry alien gets in the way and they lose track. T'Pol jumps on the table and whistles, causing Menos to blow his cover by shooting at Archer. Travis tackles Menos, who is then handcuffed and taken away.
Trip, meanwhile, initially enjoys being captain, but at dinner, he has trouble making the tough decisions— Phlox raises the question of whether or not to vaccinate the crew against a disease (since the vaccine gives people a bad stomach) and Malcolm needs to take down the warp core to continue his re-calibrations. Trip decides to postpone these decisions until later, and then the Vulcan ship arrives, with its captain, Tavek, wanting to talk to Archer.
Back on the moon, they can't take Menos to jail (since the landing area is being coated with acid as part of a repair project) so they shackle him to the bar. He denies being a thief, saying that he only smuggled as part of his cover and now has an honest job (hauling spent warp injector casings). T'Pol then flashes back to chasing Menos, but someone else was there, named Jossen. Archer wants to get Menos tried on Vulcan, but he thinks that he will be found guilty simply due to not returning. T'Pol then strips off some of the restraining straps on Menos and wears them on her feet to protect herself from the acid. She goes onto his ship to prove him wrong, but he seems to be right.
Trip talks to the Vulcan captain, pretending to be Archer, but all the Tavek shares is some info on a water polo game. Meanwhile, T'Pol admits she confirmed Menos's story and asks to speak with him alone. She asks him at phaserpoint who Jossen is, and Menos reveals that he was another operative, who was also innocent, but that T'Pol then remembers she killed. He's surprised that T'Pol doesn't remember the whole incident, since usually Vulcans suppress emotions related to bad memories, not the memories themselves. He then urges her not to "conveniently forget" what's happening now.
T'Pol then remembers everything that happened and relays the information to Archer— she was chasing seven fugitives, not six as she previously thought, and the reason she killed Jossen was because she mistakenly thought he was going to draw his weapon. The reason she previously couldn't remember was because she felt so guilty she did a memory-erasing ritual. Menos then starts a fire by turning over a table, claiming he'd rather die than be wrongly punished by law. She frees him, he runs away, and then Archer and T'Pol head for his ship.
Menos isn't on his ship, so T'Pol thinks he left on another one, but Archer isn't convinced and tells her to stay focused and wait until later to sort out the emotions. Travis then finds a secret area behind the ship, which was behind a holographic wall. Menos, who had been hiding in the area, takes T'Pol hostage and forces Archer into a locker. They have a fight, which ends with Archer telling T'Pol to trust him and her stunning Menos. They tie him up, and Travis discovers that he was indeed smuggling biotoxins after all.
Back on Enterprise, Archer offers T'Pol all the help she could need with processing the guilt.
Tropes in this episode include:
- Batman Gambit: T'Pol jumps on the table and whistles, thereby tricking Menos into blowing his cover by shooting Archer.
- Bittersweet Ending: The mission is resolved, but T'Pol must process the guilt of killing Jossen.
- Cassandra Truth: T'Pol initially believes Menos is lying about Jossen, but then she remembers that it's true.
- Flashback: We see several scenes from the past through T'Pol's memory.
- Lost My Appetite: When Phlox mentions nausea and diarrhea as side effects of a vaccine, Trip puts down his fork and stops eating his pasta.
- Manipulative Bastard: Menos. When he realizes T'Pol's suppressed memories of killing Jossen are breaking down her emotional control, he deliberately plays on that and her own self-doubt to convince her to let him go. He would have succeeded, too, if Archer hadn't been there to remind her of her duty.
- My God, What Have I Done?: T'Pol couldn't handle the guilt of killing Jossen, so she had her memory of the event blocked.
- Special Guest: Bruce Davison as Menos.
- Spoiler Title: T'Pol tells Archer that she was sent to hunt down six fugitives, of whom Menos was the last. However, the fact that the episode is called "The Seventh" should clue the audience in to the fact that that's not altogether true.
- They Wasted a Perfectly Good Sandwich: Trip doesn't get to enjoy his meal, does he?
- You Are in Command Now: Archer leaves Trip in command of Enterprise. He seems to enjoy it, until the responsibilities of command catch up to him.
- Your Favorite: Trip serves Malcolm and Phlox some of their favorite foods in the Captain's Mess.
- Would Rather Suffer: Played for Drama— Menos would honestly rather burn to death than be sentenced unfairly.
