
Picking up from where last left off, we find out that Spock is on Romulous not because he has from defected from the Federation but because he is working on reunification between the Vulcans and Romulans with the aid of a Romulan senator he met at Khitomer (Star Trek: VI.) Spock and the senator or confident in their efforts as they now have another "in" with the Romulan senate through another, younger, Romulan senator who is eager to meet with Spock and talk terms for the reunification, saying that many think that it should happen to rejoin the two people.
Spock is skeptical over the young senator's eagerness to begin reunification right away but decides to play things out to see where they end up, eventually he is captured, along with Picard and Data, as Spock's long-time friend from Khitomer was playing him all along.
The young Romulan senator, along with Sela, are eager to begin the talks of reunification but not for the reasons Spock wants, they plan to send an invasion force to Vulcan to re-conquer it and gain a foot-hold on the Federation, believing they'll have enough time to establish it before anyone realizes what is going on and take action.
Sela plans to use Spock to deliver a speech to allow the invasion force through, under the guise of being a peace envoy on Vulcan ships. Spock refuses, so Sela prepares to use a holographic Spock to deliver the message. Alone in her office for a period of time, Data, Spock and Picard manage to use the holographic imager in Sela's office to ambush her when she returns. They deliver a warning message to the Federation, rather than speech Sela had prepared, and manage to escape.
Meanwhile, the Enterprise is continuing to investigate the remains of the Vulcan ship they found in the previous episode and it leads them to a Federation border world near where they're able to intercept the Romulan invasion force but not before the ships are destroyed by Romulans.
Picard and Data prepare to leave Roumulous but Spock insists on staying still believing he can work with the young people of Romulous towards reunification. Before departing, Picard allows Spock to mind-meld with him in order to get Sarek's thoughts and feelings.
A good episode that has quite a bit going on in it from the set-up in the previous episode, but it seems like a lot happens in a very short amount of time. Namely, Spock's Romulan contact(s) being so eager to begin talks right away. Sure they end-up being skeptical over it but you'd think the Romulans would have played things out a lot more rather than rushing into this.
Sela is poorly used here and really ads nothing to the story other than as a minor callback and reuse of her character.
The episode also gives us a bit more of a connection with Star Trek VI which is a nice "extra mile" for the show to go at this point and, really, probably unprecedented for a show of the time to have such a broader universe that it connects with a recently released movie.
There's a lot of good scenes in this episode between Spock and Data and between Spock and Picard. Overall, Nimoy does a great job here.
There's some fun stuff with Riker on his investigation but, really, the Enterprise's role in this episode is pretty small and I'm not sure it was even entirely needed. (Literally everything would have turned out the same if the Enterprise did nothing.) The scenes with Riker in the Mos Eisley Cantina: Star Trek and the four-armed pianist are good.
Good couple of episodes but I think the scope of what they wanted was wider than could be contained in two episodes as it seems like a very, very truncated timeline here. Sela also seems to think, and expect, Federation retaliation to their Vulcan invasion force but seems to mostly shrug it off confident that by the time the Federation has to react they'll already be entrenched. Which, yeah, I'm sure the Federation is just going to let a core, founding, world be invaded by a major enemy power without a fight.
Some of the best scenes in the episode are between Data and Spock as they both essentially play the same role in their respective series, Data takes notice of their differences through similarity.
Again, good couple of episodes but still flawed. But they work well enough.