Rodrigo Cortez's chilling new hostage drama 'Buried' is filmed entirely in a coffin

Arguably the perfect film for our austere times, the Spaniard's minimalist thriller uses a single location, one on-screen actor, a few props (torch, Zippo lighter), a Hitchcockian sensibility and technical inventiveness to achieve levels of tension and excitement far in excess of its modest scale.

And, most impressive of all, it does this without ever going outside the four walls of a claustrophobic coffin, buried, according to American Chris Sparling's intelligent screenplay, by terrorists somewhere in Iraq.

Trapped inside this wooden hell-hole is Paul Conroy (Ryan Reynolds), a kidnapped US contractor, whose one connection with the world above ground is a mobile phone. He has just a short time before the battery runs out to come up with a $5 million ransom, or die undiscovered and alone.

Not surprisingly, Sparling's script floated around for some time before finding a film-maker. Instead of shaking his head, as others had done, when he heard it was about "a guy in a box for 98 minutes", Corts was intrigued. "I said, 'I'm interested. It's foolish enough.' It attracted my attention from the very first minute." Even so, he had his doubts, though more about the integrity of the script than his ability to film it. "I was sure it was impossible to pull off a story that could sustain that premise. I was sure that it was going to surrender, as usually happens with these small premises, and you'd have an overground sequence with explosions, a chase or whatever."

Corts decided they should produce the film themselves. That way they would have total creative control and would not have to make the kinds of concessions he had feared the screenplay would succumb to as he was reading it. His people were wary. "They said, 'Are you kidding? Nobody wants to produce it. What are you going to do with this? It's going to be dark, experimental, obscure.' I said, 'No, this is f***ing amazing. This is big. This is going to be Indiana Jones in a box. Let's do it by ourselves. We can afford a box and an actor.'"

The sparky Spaniard's only other feature, the financial satire The Contestant, was in Spanish. This time he would work in English, partly to reach a wider audience; partly, it seems, out of ego. "If I do this challenge and I do it in Spain and I do it in Spanish, it will be the same challenge but it won't have the same size or repercussions. Someone will do the remake and he will have that," he says. Basically, if there was kudos going for carrying off Buried's audacious premise, he wanted it. Corts says he also realised the film would fulfil a dream he'd had since reading about the "narrative and technical challenges" Hitchcock set himself when he did films such as Lifeboat (the title refers to the film's eponymous single location), Rope (shot in long takes which, when assembled, looked like a single, unbroken take), and Rear Window (a man in a wheelchair witnesses a crime in an apartment opposite), as a teenager. "I read about these and said, 'If I'm a director some day, I will do something that nobody in the world has ever done.'"

Having convinced his development team that he could make Buried work, he needed an actor who would also believe in him and would be prepared to be on screen, alone, for the entire running time of the film, ostensibly locked in a box.

Reynolds, who began in teen comedies such as Van Wilder but has recently branched out into more dramatic fare such as Fireflies In The Garden, opposite Julia Roberts and Willem Dafoe, had impressed Corts in John August's weird sci-fi drama The Nines. However, when the actor read the script his first reaction, the director laughs, was one of outright scepticism. "He said, 'I love it, but no way can a movie be done with this.'" After viewing The Contestant, however, he called Cortes asking to know more. "So we sent him a director's statement detailing, in 15 pages, how exactly I wanted to achieve this. And, three weeks later, we were meeting in LA. Forty minutes later, we were shaking hands."

When Reynolds introduced the film at Sundance, he told the packed house he hoped that people enjoyed the film as much as he hated making it. He might only have been half joking. After a hectic 17-day shoot in Barcelona, in which they sometimes did as many as 35 shots in a day (the normal number is around 10 to 12), the actor returned to LA, Corts claims, "with his back bleeding, his fingers literally fried, and his skin totally destroyed because of the friction of the sand."

A few days before I meet Corts, ten aid workers, including British doctor Karen Woo, were waylaid and executed in Afghanistan. I wonder, therefore, whether some people will also leave the cinema asking themselves if this is appropriate subject matter for a thriller in which, Corts says, Iraq in 2006 is just the backdrop. Although no one has been buried alive like Conroy, Corts reveals that Sparling had stopped doing research "because he found some very deep and real pain of families that lived through certain things. And, of course, our goal was different. As Hitchcock said, 'I don't do pieces of life but pieces of cake'. We were doing a high-tension thriller not a piece of reality or a documentary."

That said, he is sure they will be criticised. "Probably some people that have their sons in Iraq or whatever will say nobody should use this for a thriller. But no matter what you do in life, no matter what the options you choose, you're going to bother someone. They have their right to be angry with you, but so far we haven't had that kind of negative reaction. So let's see. We will have it, because you can't please everybody." v

Buried is on general release from Friday

• This article was first published in the Scotland on Sunday on September 26, 2010