MONSTERS (12A).

Sci-Fi/Thriller/Action/Romance. Scoot McNairy, Whitney Able. Director: Gareth Edwards.

James Cameron please take note: you don’t need to spend $200m to smack audiences’ gobs.

%movie(39088) British writer-director Gareth Edwards challenges the conventional thinking that bigger is always better when it comes to special effects-laden science fiction films with his ultra-low budget feature debut.

With a background in visual effects, Edwards sent ripples through the industry a couple of years ago by creating impressive digital trickery in his bedroom for a fraction of the normal cost.

Now, the innovative filmmaker makes the seamless transition to the director’s chair with Monsters, a brilliantly executed thriller reminiscent of Cloverfield, which puts various multi-million-dollar blockbusters to shame.

Edwards and a small team, including two actors, travelled to Guatemala and Mexico with a skeletal script, a camera and boundless enthusiasm.

The crew found locations they loved and improvised scenes, intending to stitch everything together in the editing room, where hundreds of special effects would be added to evoke a futuristic world in which aliens and humans live side by side, segregated by massive concrete walls.

This carefree approach to filmmaking sounds like a recipe for disaster, but Gareth Edwards maintains control of the various elements with aplomb.

Monsters opens with a nail-biting night vision sequence and an attack on an armoured convoy.

We flashback to bright sunshine over Mexico where womanising newspaper photographer Andrew (Scoot McNairy) must help his boss’s daughter, Samantha (Whitney Able), return home to America.

The ports are about to close and Andrew is told he must pay an extortionate fee to get Samantha on the last boat before the borders are locked down.

The only other option is to pay a smuggler to shepherd them through the infected zone where the tentacled aliens roam, which they are warned will be “a very difficult journey...very risky, very dangerous.”

Andrew and Samantha have no choice and head off into the wilderness, taking heed of one guide who tells them: “There are extra-terrestrials in the trees.”

As they near the US border and freedom, the couple encounter the gargantuan beasts close-up and discover that the real monsters might just be mankind.

From its gripping opening to the heartbreaking conclusion, Monsters holds us in a vice-like grip as Edwards creates a richly detailed future reality, aided by strong performances from Scoot McNairy and Witney Able, who have since married.

Apart from a few continuity errors, it’s difficult to tell that the film was made in such a haphazard fashion.

Everything fits together snugly and the special effects are terrific.