Ryan Reynolds stars in the claustrophobic thriller Buried. (Maple Pictures)

Alfred Hitchcock, famed for imposing formal constraints on his filmmaking, would have appreciated the technical bravado of Rodrigo Cortes, the Spanish director of Buried. Hitchcock confined one film to an apartment (Rope), another to one room (Rear Window) and a third to a cramped lifeboat (Lifeboat). But he never went so far as to set an entire movie inside a wooden coffin buried underground.

Ryan Reynolds, an actor best known for comedies, gets a real dramatic workout here. He has to start at a high level of panic and build from there.

Buried opens with a nightmare scenario straight out of Edgar Allan Poe: A man (Ryan Reynolds) wakes up in the dark, only to realize he’s in a casket under six feet of earth. There is, however, a sliver of hope. With his Zippo lighter, he discovers a cellphone lying near him and begins making frantic calls.

We learn that he’s Paul Conroy, a U.S. civilian truck driver working on contract in Iraq. The last thing he remembers was being in a convoy that was attacked. He finds out, after various calls, that he has been kidnapped by the attackers and is being held for ransom. They’ve planted the cell in his box so he can make videos to plead for his release.

The phone is his lifeline, but it’s a frayed one. The text is in Arabic and the battery is dying. When he manages to make calls, he has to contend with voicemail, unhelpful 411 operators and, once he connects with the authorities, a lot of buck passing. Frustrating enough for anyone, but imagine dealing with it when you’re inside a coffin in the Iraq desert and your air supply is running out.

Cortes makes Paul’s confinement all the more palpable by keeping us in that box with him. The camera never ventures outside its walls, and there are no flashbacks or split screens to show us the people he’s speaking to. The other characters exist only as voices — with the exception of one, seen in a video on the cellphone. The film’s light sources are limited to the Zippo, the cell’s illuminated screen and, later, a finicky flashlight. At times, Cortes plunges us in darkness, at which point we could just as well be listening to a radio play.

Like Hitchcock, however, Cortes and his cinematographer, Eduard Grau, have devised ways of allowing the camera to move within the coffin’s cramped confines. The director and screenwriter Chris Sparling throw in some additional elements to make Paul’s ordeal even more horrifying and intense – but I won’t spoil things by saying what they are.

Reynolds, the mild-mannered Vancouver-born actor best known for comedies, gets a real dramatic workout here. He has to start at a high level of panic and build from there, running the gamut from terror to rage to despair. (Needless to say, he also has to do a lot of thinking inside the box.) Again, you think of Hitchcock, who used likable, ordinary-guy actors such as Jimmy Stewart as his hero-victims.

Hitch aside, Cortes’s Buried will inevitably be compared to Danny Boyle’s 127 Hours, this fall’s other, more prominent film about a lone man’s excruciating ordeal. But Buried is much darker and includes a cruel twist that marks it as an independent feature made outside the Hollywood mainstream. And, while at first it seems to be a gimmick thriller in the mode of, say, Phone Booth, it ends up having more resonance than we expect.

As Paul gets the runaround from the U.S. authorities – including a brutally callous call from his employer’s HR manager, seeking to waive his rights to insurance – and hangs on the dubious assurances of a hostage negotiator (Robert Paterson), it becomes clear that Buried is almost as much an anti-Iraq War statement as it is a horror movie.

Then there are Paul’s repeated attempts to reach his wife (Samantha Mathis), as well as his poignant conversation with his senile mother (Tess Harper). Listening to them, you can’t help but be reminded of those last, heartbreaking cellphone calls made by the victims of 9/11 to their loved ones.

Cortes has made only one previous feature, 2007’s The Contestant, and his work to date has been largely unknown in North America. Buried should change that. He’s clearly a daring talent.

Buried opens Oct. 1.

Martin Morrow writes about the arts for CBC News.