Avatar

Pandora, the jungle moon at the centre of James Cameron's Avatar, has a lot of waterfalls.

In one scene, protagonist Jake Sully (Sam Worthington) leaps from the top of a waterfall to evade being devoured by a ferocious leopard-like beast known as a Thanator, thus separating himself from his human companions and stumbling, for the first time, into the society of the indigenous alien Na'vi – and later, Jake will engage in a crucial rite of passage alongside another waterfall, marking his full initiation into a Na'vi tribe. Breathtakingly, this second waterfall cascades out of the side of a mountainous island floating in midair, down to the lunar surface far below.

The waterfall is one of the key images (and metaphors) in Cameron's film - for while one might pause to wonder how an airborne rock no larger than a skyscraper could accommodate a river large enough to pour forth an endless onrush of water, the same hardly applies to Cameron's derivative plotting, whose origins can be traced back through the conflicted double agency of Infernal Affairs (2002) and Deep Cover (1992), the gone-native identity crises of Dances With Wolves (1990), The Mission (1986), Soldier Blue (1970) and (especially) the Tarzan movies, and from there all the way upstream to Joseph Conrad's 1902 novella The Heart of Darkness.

With waterfalls, however, the source of the stream is far less important than the arresting spectacle of its vertical descent, and there is no doubting the way that Cameron's flow of ideas has here been swept along to the next level - or to borrow another of the film's central metaphors, Cameron finds powerful new skins for the otherwise old and well-worn bones of his narrative.

The year is 2154. Jake is a one-time Marine whose battlefield injuries have left him in a wheelchair and dreaming of flight – so he leaps at the opportunity to replace his late twin brother in a scientific project being led by Dr Grace Augustine (Sigourney Weaver) on far-off Pandora. Hoping to understand better the moon's unusual biology, and to foster closer relations with the ten-foot high, blue-skinned Na'vi, Grace ensconces Jake in a high-tech sleep chamber from which he is to link his consciousness to an Avatar, a genetically engineered Na'vi body hybridised with the DNA of Jake's brother, and therefore also of Jake himself.

After his first, exhilarating tryout in his new, fully mobile Avatar body, Jake is quick to get close to the Na'vi of the Omaticaya clan, and, in particular, to their chieftain's daughter Neytiri (Zoë Saldana), much to Grace's delight – but the benevolent scientist is not the only human with an interest in Jake's progress.

The Omaticaya's arboreal home happens to sit on top of a valuable mineral seam, and Colonel Miles Quaritch (Stephen Lang), who has been tasked to clear the area for strip-mining, recruits the ex-Marine to infiltrate the native tribe, "to learn these savages from the inside", and to report back any useful intelligence – promising Jake the surgical restitution of his legs as a reward. As war becomes inevitable between the arrow-bearing Na'vi and the heavily armed human military, Jake finds himself caught between two bodies and two very different cultures.

In casting Sigourney Weaver, and in featuring near the film's beginning a scene in which soldiers catch a dropship down to an extraterrestrial surface, Cameron is clearly referencing his own Aliens (1986) – but Avatar neatly inverts that film's tropes, for here we humans are the murderous, destructive, pestilential alien invaders, and the strange-looking Na'vi are our victims.

There must be something in the water – or at least in the late-to-post-Bush dispensation – to make filmmakers once again start exploring the human in the other and the monster in ourselves, as Aristomenis Tsirbas' Battle for Terra (2007) and Jorge Blanco and Javier Abad's Planet 51 (2009) play a similar trick. Indeed, many of the last decade's anxieties have found their way into the texture of Avatar, where the fluttering ash around a felled tree evokes the destruction of the Twin Towers, where colonial wars are waged for energy resources, where neo-con phrases like "pre-emptive attack" and "fight terror with terror" trip easily off Quaritch's tongue, and where the balance of the natural environment is put at risk by human rapacity. Cameron may have conceived Avatar 15 years ago, and then waited another 11 years for filmmaking technology to catch up with his otherworldy vision – but that is not to say that, in the meantime, his screenplay has not also been updated.

It is, however, for its state-of-the-art special effects that Avatar is most likely to be cherished. Motion capture and image-based facial capture (using a head-rig system especially developed for the film) make the CG Na'vi and Avatars seem as real as the actors upon whose gestures and expressions they were built, while the landscapes that these and many other creatures inhabit have been realised by WETA digital in exquisitely exotic detail.

The result is a virtual world all at once thoroughly alien, and utterly believable, which we are invited to experience and explore as enthusiastic avatars in the cinema. The same principle of immersion applies to the film's stereoscopic 3D, which if anything is too subtle in its implementation. Its effect, more subliminal than traditional comin'-at-ya intrusive, will not be pulling anyone out of the story, but will also hardly be missed by those able to see the film only in its 2D format. James Horner's soundtrack, however, is far more conspicuous, inserting pan pipes and familiar 'world music' motifs to underscore the Na'vi's idealised harmony with their world, in what might be termed the return of the noble savage.

Still, this is hardly out of keeping with a film that traffics wholeheartedly in mythic archetypes and ecological mysticism. There is much in Avatar that is broadly drawn, clichéd even – but it is also these very things which might just earn it the status of a classic. After all, in this respect is it so very different from Star Wars (1977)? Avatar is an SF adventure both engaging and beautiful to behold, sweeping the viewer to - and over - the very edge of cinematic imagination, so that we too get to swim, however fleetingly, in the waters of otherness.