A civilian truck driver contracted to deliver supplies in Iraq, Paul Conroy (Ryan Reynolds) is attacked during an ambush and wakes to find himself buried inside a wooden coffin. He has no idea where he is located and has just a few supplies—among them, a lighter, a cell phone, and a pencil. As he struggles for breath and hopes to get help on his phone, its charge gradually deteriorating, his fight for survival suddenly becomes all the more critical when his captor calls and demands to be paid $5-million by 9:00 p.m., or else.

For a 95-minute film set entirely within the confines of a rectangular box, it is worth applauding the efforts of "Buried" director Rodrigo Cortes (making his debut American feature) for managing to keep the viewer close to riveted throughout. The main titles sequence, clearly nodding its head in style and music to the classic works of Alfred Hitchcock, sets an impossible standard right from the start that the film never quite lives up to. Nevertheless, this is a skillfully made thriller, a neat little exercise in minimalism but not exactly overflowing in depth. Screenwriter Chris Sparling doesn't go into great detail concerning his main character of Paul, developing him enough through his actions and the people he calls that the viewer identifies with him, and that's it. What Sparling is more interested in are the variations he can conceive of to keep people wanting to watch a man in such close confines that he can barely move for an hour and a half. Every time the narrative begins to drag and feel repetitive, Sparling tosses in another twist or conflict, one of the most squirm-inducing being an unwanted guest that pays Paul a visit through a hole in the coffin.

Lit by way of a Zippo, a cellular phone, a flashlight and a flare, cinematographer Eduard Grau (2009's "A Single Man") impresses in the amount of different camera setups he is able to achieve, as well as in the different shades of color that punctuate the image depending on what Paul is using for light at any given moment. The use of abrupt zooms in several scenes add to the suspense, while the music score by Victor Reyes keeps things humming along. Best of all, the proceedings never come off as stagy. In fact, it is amazing how very cinematic this story actually is; watching it from one angle on a stage would get old really fast.

Even as his star has risen in the last decade, Ryan Reynolds (2009's "The Proposal") has had to prove himself time and again as a formidable actor due to his star-making role in 2002's "National Lampoon's Van Wilder." Here, the film's effectiveness most prominently lives or dies with Reynolds' performance. He is the only one on screen, often shot in extreme close-ups. A second of artifice in his acting would immediately turn the audience off from his ordeal. Had he failed, he would have no one to blame but himself. He doesn't. Reynolds' emotions run the gamut as his Paul faces a life-or-death struggle that even he eventually realizes is probably going to end up being the latter. His attempts at saving himself and, later, his gradual acceptance of his grim fate are despairing and accurate to what someone in that situation would probably face. It's a tour de force turn from Reynolds that ought to once and for all silence his naysayers.

"Buried" ends with a clencher of a revelation and the subsequent feeling that the experience hasn't added up to as much as one had hoped. If the picture has replay value, it will be to study the technically pretty astounding filmmaking going on, not because it's a journey one would necessarily like to go on again. Script-wise, the film is as thin as the oxygen in Paul's coffin, but does the job. There is a darkly funny moment where Paul calls up his wife's friend and angrily snaps at her, then has to call her back and apologize in order to get the information he needs. Mostly, though, "Buried" is thick in portentous drama, treated as it must with a level of dire seriousness. It is a solid film that does what it sets out to do. Its point is less clear.