Star Trek The Next Generation: Crossover

Continuing the mission he began in "Unification," Starfleet Ambassador Spock endeavors to impart the logic of the Vulcan way to a small band of Romulans eager to unite the Romulan Empire and the planet Vulcan. But unbeknownst to them, a Romulan spy has joined the ranks disguised as a Unification sympathizer. Deceived by this traitor, Spock and his students are taken hostage.
Fearful that Spock's knowledge of Federation security will fall into enemy hands, Starfleet dispatches its best ship...