Star Trek the Next Generation - Unification Part 1

Spock is thought to have defected and gone over to the Romulans so Picard is dispatched to investigate and bring the accomplished ambassador home to the Federation so he starts his search for Spock with Sarek, who is very ill at this point but insists that Spock has not defected. In order to retrieve the ambassador, Picard has to utilize a cloaked vessel, so he hits Gowron and then he and Data head to Romulus and when they get there, they are taken to the literal underground and finally find Spock. What will happen next, and what did we think of this prelude to the what is probably one of the most iconic episodes of Star Trek.