It's traditional for the middle part of a trilogy to be darker than the other installments (think "The Empire Strikes Back").
"The Lord of the Rings: The Two Towers" fits this pattern, taking Frodo Baggins into territory more frightening than anything he encountered in "The Fellowship of the Ring" last year.
It also gives a starring role to Gollum, one of the most vivid - and creepy - characters in J.R.R. Tolkien's great novels.
"The Two Towers," was made at the same time and woven from the same cloth as the other chapters in Peter Jackson's ambitious "Rings" project. The similarity of the three movies - the third opens next winter - will disappoint viewers looking for something different each time.
But it ensures huge dividends for the filmmakers, now that the first installment has proved an over-the-top hit, with worldwide grosses of $860 million to date.
I found "Fellowship of the Ring" pale compared with the imaginative sweep of Tolkien's books. Few readers agreed with me - you should see the angry mail I got - so I'm pleased to report that "The Two Towers" is better.
One reason is Gollum, who dogs Frodo's trail because of his obsession with the magical ring Frodo is taking to Mordor so it can be destroyed before Sauron uses it to dominate Middle Earth forever. Gollum is treacherous and wicked, but he's also weak and pitiable. Jackson evokes these contradictory traits through one of the most ingenious computer-generated characters yet created.
"The Two Towers" also benefits from its midway position in the trilogy.
There's no need for the ponderous exposition that weighed down the first installment, since the filmmakers assume we've seen it. They give "Towers" a snappier ending, too, straining less hard to make it seem like both a single installment and a complete story in itself.
The flat dialogue doesn't give the actors much to work with, but Liv Tyler and Ian McKellen make strong impressions. And then there's Gollum, voiced by Andy Serkis, whose live performance was the basis for the computer graphics.
Most moviegoers will leave buzzing about the climactic Battle of Helm's Deep. But in my eyes, this is Gollum's show more than anyone else's, even the special-effects wizards behind the scenes.
• Rated PG-13; contains much action-movie violence.