What does it say about the second installment of Peter Jackson’s The Lord of the Rings that the best performance is by a special effect? Just glimpsed at the end of last year’s The Fellowship of the Ring, Gollum, who’s voiced by Andy Serkis (he’s being touted by New Line Studio as an Oscar candidate), is the closest thing this centerpiece of Peter Jackson’s adaptation of the Tolkien trilogy has to dramatic depth or conflict. This digitally rendered homunculus is the former owner of the Ring of Power; now debased into a sibilant, loin-clothed junkie craving his Precious fix, he’s like Laurence Olivier’s Richard III compared with the stiff-upper-lipped fortitude or leering villainy of the rest of the cast.

But nuanced characterizations and performances are not what you expect from Epics, or high-tech video games, and The Two Towers is more of the latter than the former. As Jackson gets deeper into Tolkien’s tale (and he shows here the same cinematic efficiency — if less clarity — in translating the complicated and intricately detailed narrative onto the screen with the minimum of deletions and changes), he seems to get farther from its spirit, its emotion, and its magic.

The spectacle of thousands of Orcs charging on giant hyenas or hundreds of towering Ents striding across a blighted landscape impresses only so much before you want to reach for a joy stick and get in on the action yourself. The sight of a transfigured Gandalf galloping on his white charger might stir Messianic comparisons, but he also looks like a geeky, generic wizard astride a unicorn. The way special effects can make Tolkien’s fantasy literal undermines one’s capacity to believe in it and underscores the adolescent inclinations of those who manage to do so.

Some poetry does remain — for example, the Miltonic fall of Gandalf. He thrashes with the evil Balrog barring the Fellowship’s passage through the Mines of Moria en route to Mordor so Frodo (Elijah Wood), the Ring bearer, can cast his burden into the fires of Mount Doom. It’s all a dream — Frodo’s recurring nightmare of that awful moment that splintered the Fellowship, and the story. We thus have three narrative lines, and Jackson sustains them with admirable coherence. Frodo and his faithful servant Sam (Sean Astin) have set off alone to Mordor over snow-topped mountains in a trek reminiscent of Dorothy and company’s assault on the Wicked Witch’s castle. Their friends Pippin (Billy Boyd) and Merry (Dominic Monaghan) have been captured by a gang of mutant Orcs. And the moody human wanderer Aragorn (Viggo Mortensen), along with the Dwarf Gimli (John Rhys-Davies, whose comedy is a welcome but infrequent relief) and the Elf Legolas (Orlando Bloom), have set off to find them.

The wanderings of this last group take them to the human outposts of Rohan and Gondor, where decadent realms must regird their loins to face the evil onslaught of Sauron and his lackey, the turncoat wizard Saruman (Christopher Lee). Meanwhile, Pippin and Merry have taken refuge with Treebeard (another winning special effect) and his ancient ambulatory tree people the Ents. And the hopeless task of Frodo and Sam is made easier and more complicated by the appearance of the tormented Gollum, who’s the twisted mirror image of Frodo himself.

And you thought keeping Qatar, Uzbekistan, and Yemen straight was difficult. In fact, though the subtext gets buried beneath the many, many battle scenes, for this lapsed Tolkien fan the parallels to contemporary events are where the real interest lies. Tolkien denied that his work was an allegory, and he may be right. It’s more of a template, a vivid outline of the power struggles endemic to history, its application shifting with each new look and new era.

In the first cinematic episode, I thought the evildoers Sauron and Saruman were stand-ins for bin Laden and al-Qaeda and the Axis of Evil. But now I’m not so sure. As Saruman cuts down all the trees in his kingdom, strip-mines its resources, and mechanizes his realm into a polluting cistern of mindless clones, it looks more like a Republican vision of America. And if you straightened out Gollum’s posture a bit and put him in a suit and a tie and a cowboy hat . . .