Assuming that anyone viewing this film has seen the first instalment, or is at least familiar with the story thus far, there is no opening exposition, and it's straight into the action, if only for a brief while. The Two Towers opens slightly before The Fellowship of the Ring left off, with Gandalf (Sir Ian McKellen) and the Balrog plummeting through the abyss, battling with each other on their way to what seems like certain splat.

This segues wonderfully into Frodo (Elijah Wood), distraught at the death of the wizard, awakening from a dream of his friend's demise. He and his trusty friend Samwise (Sean Astin) are continuing their journey to the land of Mordor, domain of the dark lord Sauron, to destroy the One Ring and bring freedom back to the peoples of Middle Earth. They are joined on the journey by Gollum, a curious-looking creature who possessed the ring for 500 years before losing it to one Bilbo Baggins, uncle of young Frodo. Having been so long under the evil influence of the ring, Gollum, once a Hobbit-like creature by the name of Sméagol, is now a twisted and pathetic being, obsessed with regaining his 'precious' ring.

Sméagol/Gollum is a key character in the story, and Jackson had to be careful not to make the former ring-bearer a comedy figure. In this he has succeeded wonderfully, and the bods at his special effects studio have really done the business. Gollum is a fully-formed personality, not a mere two-dimensional character or a pointless figure of fun that will leave fans fuming (step forward, Jar Jar). He is the most impressive CG character yet seen on film, and the interaction between the actors (notably Wood and Astin) and the pixellated star is nothing short of brilliant. As well as this, Gollum is a most individual creation. His creators, when designing a short, funny-looking creature with few hairs and bizarre speech, must have been acutely aware of the possibility of coming up with Yoda.

After an unsuccessful attempt to wrest the ring from Frodo while he slumbers, Gollum is subdued by the hobbits, and agrees to lead them to the land of Sauron. Gollum's fate, like Frodo's, is inextricably linked with the ring, and as he guides the hobbit pair to Mordor, we begin to see the effect that the ring has had on him, and it is hard to decide whether Gollum should be despised or pitied. This is even more of a dilemma for Frodo, who, with each step towards the place of the ring's creation, and the dominion of its master, comes ever more under its dark influence, and Gollum becomes not so much Frodo's enemy as his future. Although the ring-bearer's quest gets less screen time than the other two stories (Merry and Pippin's experiences with the Ents, and the assault by Saruman's forces on Rohan), it is this interplay between the hobbits and Gollum that provides the moral heart of the movie.

Elsewhere, Legolas (Orlando Bloom), Aragorn (Viggo Mortensen) and Gimli (John Rhys-Davies) continue from where we last saw them in Fellowship, tracking the Uruk-Hai who have abducted Merry and Pippin. Believing them to have escaped from their goblin captors into Fanghorn forest, the trio follow their trail into the woods and encounter the re-born Gandalf, now going by the sobriquet 'Gandalf the White'. Though he appears to have lost some of his memory, he has lost none of his potency or his charm, and Ian McKellen is once again faultless as the man with the staff.

Gandalf leads Aragorn and friends, knowing of Saruman's intention to invade, to Rohan, where they receive a less than warm welcome in the hall of King Théoden (Bernard Hill), where the decrepit king sits in the control of Saruman's spy, Grima Wormtongue. A furious Gandalf expels Wormtongue from the land, and heals the king, who regains strength and mind. Learning that the invasion forces are on their way, Théoden orders the evacuation of his capital, and all depart to the ancient Rohirrim stronghold of Helm's Deep. Thus the scene is set for the climactic final battle.

Not forgotten are the two mischievous hobbits Merry and Pippin, who are befriended by Treebeard (voiced by John Rhys-Davies, who also plays Gimli), an ancient, tree-like creature who was once befriended by Saruman the Wise (Christopher Lee, again on top form). Treebeard is an Ent, or tree-shepherd, one of an ancient, and now scarce, peace-loving race who talk with the trees and tend the forest. Upon learning of Saruman's treachery, Treebeard summons a council of Ents, and they turn their attention to Saruman's stronghold of Isengard.

Treebeard was another challenge for the special effects experts, being little more than a walking tree, but as an important character in both novel and film, he had to be as real and as serious as possible. Given that seeing trees walk is not an everyday occurrence, Jackson's team have done a splendid job of making the character believable, if not with quite the same aplomb with which they tackled Gollum. In fact, all of the special effects in the film are impressive, not least the hordes of orc and Uruk-Hai warriors that besiege Helm's Deep in the movie's stunning 45-minute climax, quite probably the finest battle-sequence ever committed to celluloid. With all this incredible computer artistry on display, it is a cause for no little wonder that the ancient blue-screen technique should still look so bad. At one or two points in the film this technique is very obvious, and takes away from the polish, but it is nothing worth going on about.

"Well," I hear you ask, "is it any good?" Despite having a darker tone than The Fellowship of the Ring, The Two Towers does contain quite a lot of humour, often at the expense of Rhys-Davies' Gimli, or Gollum. However, some of this humour sits uncomfortably with the action around it, and detracts from the tone of the scene. Also, some of the dialogue feels a little clunky, particularly where Jackson has strayed from the source material and needs to explain part of the story. These are minor niggles, though, and The Two Towers is another masterpiece from Peter Jackson. It's impact is less than Fellowship, but this is perhaps due to the fact that the audience now knows what to expect. The action is smooth and well-directed, and the performances generally excellent all-round, with particular credit going to Andy Serkis, who provides the voice of Gollum and who brings real life to the character.

Despite having more action, it is not quite the movie that its predecessor was, and judged against The Fellowship of the Ring I would give it 4 out of 5. On its own, and this is how I will judge it, it's another five CGU (Combined Goodness Unit) effort from Mr Jackson. Can't wait till next December...