This is how you make a sequel. Instead of just being a tacked-on continuation or brazen cash-grab, "[REC] 2" builds upon the mythos set up in 2007's "[REC]," then twists it in rousingly unanticipated ways as the characters—and viewers—learn more about what they are dealing with. Returning to the directors' chairs, Jaume Belaguero and Paco Plaza find logical ways to also retain the POV style of the original. This "you-are-there" feel, aided by superb actors who never seem as if they are acting, creates a strong sense of disquiet and foreboding. Anything could be lurking around the corner or at the edges of the frame, and half the fun is in the diverting of this anxious anticipation just as the real scares prepare to pounce when you least expect them to.

A city apartment building has been quarantined from the outside world, some kind of contagious virus having turned its inhabitants into raving, drooling madmen. Enter a SWAT team equipped with helmet cameras who, led by Dr. Owen (Jonathan Mellor), are tasked to make their way inside, search for survivors, and find a possible antidote hiding somewhere in the cellar apartment—the root of the outbreak. Dr. Owen knows far more than he's letting on, however, and it doesn't take long for all hell to once again break loose. Meanwhile, three teens (Andrea Ros, Pau Poch, Àlex Batllori) wielding a camera find their way inside via the underground sewer system, not realizing just how fatal this decision is about to become.

A study in nightmarish realism, "[REC] 2" comes off as a natural extension to its raw, startlingly creepy predecessor. Whereas "[REC]" and the American remake, 2008's "Quarantine," took their time setting up the story and pulling the viewer in before its gradual ascension into pure terror and horror, "[REC] 2" is faster and more unstoppable—an edgy, frightening thrill ride sometimes reminiscent of a (really good) first-person video game. By the start of the picture, the crap has already long since hit the fan, and now it is up to Owen, the SWAT team—and later, the three teenagers who have broken in—to survive the ordeal long enough to capture a blood sample from the virus' source, an emaciated, zombie-like girl named Niña Medeiros (Javier Botet) who is lurking about the property.

The scenes set in the cellar apartment are, once again, thick with overwhelming tension, and a set-piece set in an air shaft is enough to suffocate the most jaded of audiences. It goes without saying that the inevitable appearance of Niña Medeiros—the physical embodiment of one's greatest fears when they go to bed at night—is just about as teeth-chatteringly scary as it was the first time around. Javier Botet, ultra-skinny and lanky and no doubt draped in top-notch make-up effects, is stunning in the most chilling of ways as Niña Medeiros. Also at the top of their games: newcomer Jonathan Mellor as the determined Dr. Owen; Andrea Ros as Mire, the most reluctant and vulnerable of the teens; and Manuela Velasco, welcomely returning as reporter Ángela Vidal, lead protagonist of the first "[REC]," who has survived within an inch of her sanity.

There is very little that is thematically deep about either "[REC]" or "[REC] 2," but they both make up for it in their educated, tightly-crafted know-how of the horror genre. Directors Jaume Belaguero and Paco Plaza are well aware of how to toy with their audience, tossing them through the veritable wringer. With "[REC] 2," they do not merely repeat themselves, but bring added insight to the plot, turning an unthinkable biological hazard into something that, as it turns out, is also hauntingly supernatural. With suspense raised to the rafters, the film concocts a number of third-act revelations that deliciously expand the scope and pave the way for a third film in the series. The mere prospect of such is exciting, indeed. Bring it on!