Where once the point of CGI in cinema might have been to produce images of crystalline, almost architecturally detailed clarity, now its future seems to lie in smudging, smearing and making indistinct. This terrifically exciting sci-fi movie from smart young British film-maker Gareth Edwards is a case in point. His digitally created beasts, and the exotically wrecked landscape they inhabit, seem to have been created from a kind of social-realist grime. It's strictly 2D: Edwards is the anti-James-Cameron. The effects don't draw attention to themselves: tentacle-waving aliens are all part of the general, grubby absence of law and order.
Monsters has been widely, and with good reason, compared to Neill Blomkamp's apartheid satire District 9, which also imagined extra-terrestrials in a post-awe spirit. These dirty, ramshackle creatures were just another species of the dispossessed, to be feared and hated by the white overclass. Edwards's movie imagines that Nasa received news of alien life out in the galaxy, sent up a space probe to recover some of its seeds and spores, but that the returning craft crashed in Mexico, where the aliens came to grow and roam, turning that entire nation into a bio-hazard zone. Could the panicky US authorities have deliberately allowed the alien-bearing spacecraft to crash down Mexico way, thus keeping the yucky immigrant aliens well out of American territory? Either way, the situation is now a Swiftian cartoon: the rich nation fearing its poorer neighbour. It is here that photojournalist Kaulder, played by Scoot McNairy, finds himself on assignment, snapping the aliens and their human victims. He is furious to be ordered to "babysit" his boss's beautiful, vulnerable daughter Samantha (Whitney Able), accompanying her through the ultra-dangerous alien zone to the US border. Inevitably, their relationship begins to change.
Both the satire and the human story are more involving than in District 9, and McNairy, in particular, gives an excellent and very convincing performance. This is a very postmodern sci-fi, with its downbeat approach to the monsters themselves, but with a hugely involving love story. Edwards's movie – he writes, directs, produces and creates visual effects – has also drawn explicitly on classic models. He channels the upriver nightmares of Herzog and Coppola, with a strong streak of Spielbergian wonder at the sight of two aliens apparently dancing, or communicating, or having sex – an epiphany that sets the seal on the humans' relationship. And the final sequence in which Kaulder and Sam gaze at the protective great wall America has created, musing on how America looks from the outside, is a superb final gesture: mysterious, daunting and sad. The idea of a "journey" has become absurd in the age of reality TV. Yet this one has really meant something.