The best Star Trek movies have featured a wild card. Star Trek II: The Wrath of Khan had the witty, demonically virile presence of Ricardo Montalban, who seethed and flashed his amazing pectorals as the evil Khan. Star Trek IV: The Voyage Home plopped our heroes down in contemporary San Francisco for a good- natured clash-of-cultures bash (the movie was so entertaining it was easy to forgive the fact that the plot was about saving whales). In each case, there was something to remind you that you were watching a real movie, and not just a revamped '60s TV show featuring actors with too much waistline and not enough hair.
But then there are the other Star Trek films, the ones that are simply glorified television episodes. Of these, Star Trek VI: The Undiscovered Country would fit most cozily onto the small screen. Though touted as the absolute final chapter (yes, fans, it really is time to get a life), this is no big wrap-up, no cosmic stunner. Star Trek VI is just pleasantly diverting, business-as-usual hokum, with the Enterprise crew at the center of an intergalactic standoff between the Federation and the warlike Klingons. The whole thing is a vague racial-political allegory (it's sort of a cross between the Middle East crisis and the end of the Cold War), but what else is new? The series was every bit as ''relevant.'' Wearing a ton of melty plastic, the always enjoyable Christopher Plummer appears as Chang, a glowering Klingon general who keeps quoting his favorite authors but otherwise doesn't get enough to do. The main pleasure here is the low-rent yin-and-yang interplay of William Shatner and Leonard Nimoy now cheeky, now philosophical, now spouting impassioned techno-jargon. How could the next generation ever hope to top these jokers? B-