Holding grudges

A horror movie is bad if it:

1) Destroys itself with a melodramatic ending, chase scene or action sequence.

2) Fancies itself a serious commentary on the state of the human psyche.

3) Stars Johnny Depp and a not-very-ominous black hat.

4) Is “Exorcist: the Beginning.”

5) Makes no sense.

“Ju-On,” the Japanese horror flick on which “The Grudge” is based, consistently broke rule number five, but I enjoyed it anyway, assuming that I was confused because I am an idiot with no understanding of Japanese culture and not because there was no sense to be made. I knew that, in the U.S. version, I could look forward to being spoon-fed an oversimplified plot explanation and not-so-dazzling CGI effects, and that’s exactly what I got.

Karen (Sarah Michelle Gellar) and her doe-eyed metrosexual boyfriend, Doug, move to Japan to go to college together because they love each other soooo much and they’re going to have a happy life. Then Karen volunteers at a clinic for crazies and a plot I once thought too complex for my ignorant ass to

understand is transformed into the flippant story of a contagious haunted house.

Achoo! Karen learns the hard way that, long ago, an evil energy sprouted from a brutal murder and stayed in the house to infect all who enter, compelling the victims to commit suicide, kill someone else or become drooling zombies until the evil comes back for them.

The indiscriminate evil in “The Grudge” does whatever the fuck it wants: kill, maim, harass, paralyze or make victims disappear off of the face of the earth. It can even rip off body parts. Some bodies rot and some are never found again. It can be a hairy, formless dark thing, a grey and scabby Japanese woman or a blue little boy with a cat. It can crawl down the stairs to kill you or lure you to the attic with mysterious footsteps.

And what the evil does with its victims, it seems, depends on the pecking order of the stars: a

foreign nobody actress gets her jaw ripped off, Clea Duvall suffocates, Gellar is shaken up — and ugly (this, however, is no fault of “The Grudge,” but a case of bad genes).

Horror movies have to adhere to a set of rules, goddamn it. Freddy can’t kill people who aren’t sleeping, Jason waits for his victims to make sweet love and Pinhead needs someone to play with his box. It’s true that these are all franchises and “The Grudge” is just one movie (so far), but there are 82,000 “Nightmare on Elm Street” movies for a reason: a halfway-dependable structure that dumbshits like me will keep paying (and paying) money to see.

“The Grudge” is scary, if only in a “this would be a lot scarier if I knew what the fuck was going on” kind of way. There are blood, guts and surprises, and the main ghost makes a disturbing throat noise

that is horrifying. Even if you emerge from the theater thinking about the popcorn stuck between your teeth, later on you will find yourself staring wistfully down dark hallways and checking behind the shower curtain to make sure no one dead and scabby is hiding in the tub.