When Hollywood studios acquire foreign properties and try to remake them, the results are famously hit-and-miss. It is for this reason that expectations were not very high for "Quarantine," based on the smashing (and, at the time of this writing, still unreleased in the U.S.) Spanish horror film, "[REC]." Would an American crew dumb things down for audiences, going for cheap thrills and condescending storytelling over the original's more penetrating and cerebral aura of fright? The answer, it is heartening to declare, is no. Promising writer-director John Erick Dowdle and co-writer Drew Dowdle (their much-acclaimed, much-delayed debut, "The Poughkeepsie Tapes," currently gathering dust on MGM's shelf) stay mostly faithful to "[REC]" while diverging just enough to make this new version their own. They have managed to improve upon certain aspects while not living up to other things that its predecessor did better. Measured out overall, they are close to equals.

Told exclusively from the point-of-view of a cameraman's lens, the film immediately introduces Angela Vidal (Jennifer Carpenter), host of a television show called "Night Shift." She is at a fire company, all set to spend the overnight hours there as she reports on the profession of firefighters. After interviewing the employees and getting particularly chummy with one of them, Jake (Jay Hernandez), the alarm bell sounds. Angela and cameraman Scott (Steve Harris) excitedly ride along with them to answer the call of an apartment building where screams from an elderly neighbor have alarmed the other residents.

No sooner have they entered and gone up to Ms. Espinoza's (Jeannie Epper) apartment that the woman, foaming at the mouth and disoriented, suddenly attacks one of the rescuers. Escaping back down to the building's atrium, the group discover that police and government officials have surrounded the building, quarantining the inhabitants and refusing to let any of them leave with their lives. As sickness spreads among them—Lawrence (Greg Germann), a veterinarian, surmises from the symptoms that it's an extreme, highly contagious form of rabies—Angela, Jake and Scott desperately attempt to find a way out.

"Quarantine" follows the basic outline of "[REC]" while tweaking it here and there. At 89 minutes, the screenplay has been expanded, adding in a few more scare scenes, a few more clues as to what is going on amidst the chaos, and a few more character moments. This latter addition is certainly an improvement; whereas the characters in the earlier film mostly blended together, not really getting a chance to stand out from the crowd, the ensemble here are much more individualistic and their almost wholly dire fates more coherent and effective. Tiny inserted details, such as the pet that is seen running out of Ms. Espinoza's apartment, or the hostile rat that Scott stomps on with his shoe, are welcome, building upon the mysterious, bone-chilling mystique of the viral outbreak.

By and large, the creep factor is also increased, the suddenly villainous, no longer completely human antagonists more unsettlingly zombified in their features. With the camera swirling frantically and madness taking over the people's DNA, the film takes you back to the same feeling you got as a seven-year-old attending a radio-sponsored Halloween attraction. Afraid to inch around corners but demanding rapidity as drooling lunatics come at you from every direction, the audience tightens their grip and edges to the end of their seats. Director John Erick Dowdle is terrific at building intensity levels to near-unbearable crescendos, and also throwing in subtle hints and background action that may not be caught the first time through.

Jennifer Carpenter (2005's "The Exorcism of Emily Rose"), as Angela, deserves credit from venturing far and beyond the typical call of duty in a horror film. Not content to just scream and look frightened, Carpenter goes one step further by hyperventilating and falling into helpless bouts of pure hysteria. Some viewers may accuse her of overdoing it, but the actress embodies a more despairing, authentic range of emotions that someone in her situation really would experience. With that said, Carpenter is not as personable or warm as first pic's lead actress Manuela Velasco, and her news reporting skills suggest that she's been on the job for less than a week. The rest of the cast is superb, making the most of their fleeting screen time as the camera roams this way and that to catch all the goings-on. Of them, Jay Hernandez (2008's "Lakeview Terrace") makes the most imprint as Jake, an upstanding professional at the end of his ropes.

The biggest flaw of "Quarantine" is the crucial climactic scene that was easily the highlight of "[REC]." For a movie that thus far has done a better job of trying to explain what is happening, director Dowdle goes in the opposite direction with the ending and makes the unfortunate choice to cut out some of the crucial backstory of a key last-scene character. Because of this, the tension comes not from anticipating what is about to show itself to Angela and Scott, but from the unholy levels of mess-your-pants terror Jennifer Carpenter exhibits and spills out into the audience. This nightmarish figure that does ultimately appear, by the way, is nowhere near as horrifying as in "[REC]," looking more like an unkempt man than the emaciated abomination that haunted the earlier movie. Of all that Dowdle gets right, he gets this unfortunately wrong.

Notwithstanding the most shameless example in memory of a theatrical trailer giving away a movie's very ending, "Quarantine" is unnerving, jolting entertainment that, lo and behold, mostly does "[REC]" proud. The film is completely unnecessary, to be honest, but if a remake must be made in lieu of original thoughts and ideas, one could do far, far worse. Putting to complete and utter shame George Romero's manipulative, badly-acted, insultingly-conceived recent POV zombie film, "Diary of the Dead," "Quarantine" is the real deal—a primal, uncompromising vision of insanity run amok.