Nominated for a BAFTA for Outstanding Debut, writer-director (and cameraman) Gareth Edwards would have been a far more deserving winner than Chris Morris for Four Lions. Still, he did pick up Best Director, Best Achievement in Production and Best Technical Achievement awards at last year’s British Independent Film Awards for his edgy sci fi road movie thriller, shot with a crew of two, for a budget of just under £311,000 and using digital effects programmes on his PC.

Set six year’s after a NASA probe crash landed in Central America after returning with samples from Jupiter’s moon, Europa, the alien life forms that emerged have caused half of Mexico to be quarantined as the Infected Zone with the military trying to contain them.

There to get a shot of them on the move, photojournalist Andrew Kaulder (Scott McNairy), is ordered to find his wealthy boss’s daughter , Sam (Whitney Able), stranded in San Jose while vacationing before her impending marriage, and reluctantly escort her safely across Mexico and back through the wall that runs along the American border, before the creatures’ migration becomes too active for safety.

But, there is a rapidly closing window of opportunity to get to the boat in time. If they miss it, then there will be a six month wait before safe travel is again possible. So, inevitably, various situations first conspire to slow them down then, after finally arriving and booking passage, an ill-advised drunken night leaves them unable to board.

The only solution is to trade her engagement ring for an armed escort through the Infected Zone. Naturally all does not go smoothly, leaving the two of them travelling alone, the nature of their relationship shifting in the process, before arriving at their destination to be greeted by an unexpected nasty shock.

Now, if that brief synopsis, the genre and the film’s title lead you to expect another Skyline, you can happily think again.  Closer comparisons might be Tarkovsky’s Stalker (if you happen to be an art house buff) and District 9.

This isn’t about aliens on the rampage and plucky humans fighting back, but rather a story of love forged from danger underscored by a strong metaphor about those humanity calls monsters, although Edwards has said there was no intended specific allegory about the USA, Mexico and illegal immigrants.

Other than a brief glimpse through night vision camera in the opening moments, no creature appears until the final moments when, at a deserted gas station and featuring what sounds like whale mating cries, Edwards poetically delivers the title’s not entirely unpredictable irony.

But if there’s no action money shots, there is plenty of palpable tension and pervading air of menace. The devastation caused by the creatures may happen off screen, but the effects are obvious. Edwards has a keen eye for creating a mood through the lens – the eerie darkness of the gas station lit by muted neon, the scene in Andrew and Sam spend the night atop an ancient ruin, the landscape spread out below them – but the film wouldn’t be half as effective without the score by Jon Hopkins and the credible performances by and chemistry between McNairy and Able that makes their flawed characters so, well, human.