What is zero?

Maybe it's nothing. Maybe it's sumless. Maybe it's empty.

Or from a certain point of view, it's everything. It's the beginning, the start, the foundation.

The true zero of my geek life can be found in a few places, but the spot that's perhaps fondest in my heart is "Star Trek II: The Wrath of Khan." It's the perfect candidate for Essential Geek status, because it's an unparalleled classic. But for me, it's doubly important; it's not just essential to understanding and enjoying geek culture, it's essential to me as a geek as well. It's deep in my nerd DNA like few other films or TV shows or comic books or video games or actors could ever be.

Which is odd, because at first glance, "Khan" hardly seems like Trek at all. There's no exploration of strange new worlds, no new life forms or civilizations. If you're looking for archetypal Trek, any of the best episodes of the original "Star Trek" series or "Star Trek: The Motion Picture" will serve you far better--they're the template from which Trek as we know it was born and raised.

Regardless of the prototypical Trekness of "Khan" or lack thereof, the proceedings feel epic anyway. That's largely because of the film's sweeping command over theme and character, two aspects that are most definitely central to all great Trek. "Khan" may be best known among geeks and non-geeks alike for classic lines such as "I have been, and always shall be, your friend" and "KHAAAAAAAAAAAAAAAAAAAAN!" But beyond the dialogue and Ricardo Montalban's perfectly-feathered hairdo, there's an elegant plot suffused with tension and meaning, and enhanced by terrific acting.

The beating-to-near-bursting heart of this flick is its performances, and the greatness starts at the top. Let's just come right out and say it: This is William Shatner's finest performance. (Sorry, "T.J. Hooker" fans. Your time will come.) This is not the cocky, conquering Kirk of the original "Star Trek" series. Instead, we view the portrait of a man slowly inching past his prime who must decide whether to burn out as a starship captain or fade away behind a desk at Starfleet Command.

Throughout the film, Shatner uses his swagger as a mask to cover a frightening realization: He's getting old, he will die, and there's nothing he can do about it. (Nothing, that is, except appear five Trek films later in a far crappier movie, where he finds himself transported by sheer plot mechanics to another era and suffers a pathetic death at the hands of...are you ready for this?...MALCOM MCDOWELL. Man, I hate "Star Trek: Generations.") In contrast, Kirk's old adversary Khan has pitched himself into a megalomanaical frenzy following his wife's death. Khan is hundreds of years old, and yet he mocks death in his quest for revenge. He blames Kirk , and Kirk knows what he blames him for, and that's the character dynamic in a nutshell.

The film is basically the Kirk and Khan show, with their furious battle--one to wreak vengeance, the other to prevent its path of destruction--situated at center stage. There are big ideas here, and yet they play on a microscopic level within the vastness of this outer space that the Trek franchise has dedicated itself to exploring. Inside this tiny speck of existence, this incomprehensible blip along the timeline of the universe, is our strange new world, the place where we and the characters must boldly go. It's an amazing feat to watch unfold before your eyes--a sci-fi story that chooses to stay small, a battle where the stakes may be high but the encounters are close and almost intimate.

The initial battle between Kirk in the Enterprise and Khan in the hijacked Reliant is a classic example. Throughout, as Reliant decimates Enterprise and Kirk is basically caught with his britches down, the tension is reminiscent of the clasutrophobia a great submarine movie can induce. It boils down to a duel of wits, played out over communications channels in an electric scene for Shatner and Montalban. The day is won not through furious fighting and dazzling FX, but through Kirk's simple outsmarting of Khan. And even in the victory lies regret...the regret of a once-great starship captain second-guessing his own abilities in the face of his ever-creeping-onward age.

"Khan" is structured so tightly around Kirk and Khan that when Spock nobly sacrifices his own life to save the Enterprise in the movie's closing minutes, the emotional blow is all the more unexpected and powerful. The Enterprise's science officer slips down a ladder, knocks Bones out cold with a quick Vulcan nerve pinch, and saves the day...but not himself. Though it's one of the most impacting moments in sci-fi history, what makes it truly remarkable is its deeper meaning, the way it reverberates back to the film's central character and theme.

Although it's Spock who demonstrates how the needs of the many outweigh the needs of the few (or the one), it's Kirk who is left behind to learn the difficult lesson of his friend's noble task. James Tiberius spends the film avoiding death--cheating it, and then patting himself on the back for his ingenuity--and yet, in the end, death is shoved into his face, and he's forced to deal with it. His friend's demise pushes him forward out of the future to which he's resigned himself.

Right on. That explains why it's essential to geekdom...but why is it essential to me? A harder question to answer, but I'll try, and I'll do it short and sweet: To me, this movie is exquisite. These are characters I love in their finest moments, being funny and interesting, brave and flawed, real and beyond real all in the same moment. This is a franchise I love at its peak of creativity. "Khan" is a story that's carefully crafted and cleverly plotted with brains to spare. Every time I see it, I marvel at its greatness...so complex and rich, yet playing out so smoothly. They all make it look easy. Best of all, it's a damn fun time at the movies.

Damn. That sucks. I didn't quite capture it. But then, it's always hardest to properly express the way you feel about the things you really love.

"Star Trek II" is currently available on DVD in an excellent two-disc edition that features a director's cut of the film, a fantastic commentary track by director Nicholas Meyer, and some other cool extras. You might want to adjust the brightness on your television set when you watch the vintage interview clips, though--the cast is bedecked in some vividly frightening 1982 outfits. The cheap among you can channel surf Spike TV, USA, and Sci-Fi in the hopes of catching one of their occasional broadcasts of the film, but the "Khan" DVD belongs in any true geek's film library.

The original Enterprise crew appeared in four more films following "Star Trek II." But the Trek films have never again found that perfect mix of tone, characterization and action they achieved in "Wrath of Khan." It's a meditation on morality, a taut battle against insurmountable odds, and a bevy of classic moments--in short, Trek's finest voyage.

Matt Springer has been writing professionally about genre entertainment for the past five years and has worked full-time for such publications as the Official Buffy the Vampire Slayer Magazine, Cinescape, and Total Movie. He co-edits the genre criticism website Entertainment Geekly (http://www.entertainment-geekly.com). His first novel, Unconventional, is the tale of three geeks who spend a life-altering weekend at a convention; buy it online at South Side Press (http://www.southsidepress.net). He's currently working to become a sitcom writer.