The horror genre is the cruelest in cinema. Though a not-terribly funny comedy may be genial enough to give it a pass, it's fair to say scares are cut and dried. And, for all the genre entries, most movies aren't that scary, and many modern films can't even deliver on the promised "Boo! Scares" of a door slammed shut or a zombie showing up in an improbable place. For the most part horror filmmakers are just as willing to rely on gore. But there's an art to a good scare film, and the lower fidelity the better; CGI just isn't scary. But more than anything, horror is about tone, and what Paranormal Activity does absolutely right is never let the viewer off the hook. Katie Featherston and Micah Sloat star as themselves (essentially) as a couple who records the supernatural happenings at their place. My review of Paranormal Activity after the jump.

The film is fairly familiar to those who remember The Blair Witch Project: Micah owns a camera, and decides to time lapse the evenings to show what's been going on. They've talked to a psychic (Mark Fredrichs), but he offers nothing of value. It seems that a spirit or demon is following Katie around, and it's just getting worse. And as the film progresses the evening episodes become more and more frightening.

Ultimately, there's not much plot to chew on with a film like this, nor should there be. There are also a lot of boring parts and slow parts in the beginning. But horror benefits from people getting fidgety and anxious, and the tension of being a little bored always pays off, because it keeps the audience on edge, and that comes from having the limited POV of one camera, and the complete lack of a soundtrack. It tells the audience they can't be positive about what they're about to get, and unsure when the hammer is going to drop. The effects here are simple in execution, but brilliantly delivered, and director Oren Peli orchestrates them with the right sort of deliberate pacing that showcases how it's often the moment after the audience has looked everywhere that you should hit them with a jump scare. And in a lot of ways, there are sequences in this that remind me that the Ben Gartner's head falling into frame in Jaws is one of the great scares in cinema. It's all timing.

One of the other great things about the film is how so much of it is accomplished by the audience's imagination. It's not hard to rig a door with wire to get it to open or close violently, you don't need digital trickery or a million dollars to achieve such effects, but seeing a door opening handlessly in this film got the audience gasping. And though Paramount successful sold it as an underground hit, the film managed to be more satisfying to a mainstream audience than The Blair Witch Project. Paranormal Activity hit festivals in 2007, but it took everyone a while to figure out the best ending for the movie. They found it, and though the supernatural elements don't leave me with the same sort of existential dread as The Blair Witch Project, Paranormal Activity is an absolute blast, and can get you jumping at the smallest movements while watching it in your house alone. This formula, the no budget one-camera thing can't really be imitated, at least for a while, but when they get it right, it shows how horror should work.

Paramount's Blu-ray comes as a two disc set, with the second disc a digital copy. The film starts with no main menu, and the feature is presented in 5.1 DTS-HD and in widescreen (1.78:1). The picture quality is as good to be expected of something shot on a high-def home camera, but the surrounds are the film's biggest cheat, and strongest asset. After the film is over a list of people who supported the expansion run of the film are listed, and then you get a list of options against a black screen, and that's it for a non feature menu. Extras include an alternate ending (6 min.) which can be watched on its own or with the feature. This is not - however - the ending the film first went out with. There's also a trailer for Martin Scorsese's Shutter Island.