Episode Star Trek: The Next Generation S5E07 · 2368

Unification

Two-part episode; part one

Unification
Image: TMDB

Picard goes undercover on Romulus in search of Spock.

Picard learns that Ambassador Sarek, the Vulcan diplomat, is dying, and that Spock has gone to Romulus. Picard decides to investigate, and, with Data, goes undercover to enter Romulan territory. He is looking for Spock and the explanation for his actions.
The episode features the return of Spock to the franchise, an event for fans, and it is a link between the original series and the new one. The story builds slowly, with emotional scenes at Sarek's bedside, and sets up the mystery of what Spock is trying to do on Romulus.