The Alien saga always took Earth as its lost object, and specifically the apocalyptic possibility of the Alien someday reaching Earth. It's appropriate, then, that Ridley Scott's prequel opens on prehistoric Earth, jumps forward to future Earth, and then dovetails them into the expedition to discover why the 'Engineers' - another species of alien - both created humans and then invented the Alien itself to annihilate them. The reasons why they failed form the substance of the film, which distinguishes itself from previous films in the saga by drawing on the romantic, wondroua side of cinematic science fiction, and the scientific, classicist side of literary science fiction - for the first half at least, it's very much in keeping with Jules Verne and H.G. Wells' vision of science fiction as resolutely Earth-bound, the attempt to explore and map the deepest temporal and spatial recesses of our planet. The devolution into more recognisable horror isn't as gradated or as elegant as it could be, but it's still idiosyncratic, and Scott manages to do a lot with a script that would seem to offer him very little scope for nuance and indirection. In particular, his treatment of actual physical sets is incredible, and frequently on a par with anything in the original film, no small achievement given that they effectively retread and extend the same world. More generally, his direction is spectacular whenever it focuses on any actual physical texture - the entire narrative is set in place by a cave painting and a subsequent 3D lecture on cave art. As this might suggest, there's two distinctive uses of 3D in the film as well. On the one hand, there's the expected, cavernous deep-focus shots, but there's also a use of 3D in the service of texture as much as depth - and, in particular, surfaces which are on the verge of becoming organic, of taking on the extra dimensions of a living membrane, whether in the form of the ship's wallpaper or the new alien's odd regenerative power. Although the individual aliens themselves are fairly underwhelming, at digital odds with Scott's cold, analog sublimity, this attention to texture does mean that H.R. Giger's maelstrom of limbs and organs is envisioned in perhaps the most appropriate way possible - as a frieze, a mere frozen moment in a ongoing process of visceral metamorphosis that becomes more or less continuous with the film's main cavernous spaces. In other words, it's the closest we might get to a Giger gallery, and that tends to make the human narrative somewhat redundant, which is fortunate, since screenwriters Jon Spaihts and Damon Lindehof seem to have used the existence of the Engineers as a pretext for making every human character repetitively robotic, albeit in a way that makes the only robot strangely and warmly human.