"Silent Night, Deadly Night" takes off from the notion that Santa Claus is an ax murderer, but it never quite lives up to the delicious perversity of its premise. An idea this shocking has to be earned; instead, director Charles Sellier Jr. ("The Boogens") gives us another casually constructed splatter flick that has more to do with morbid arithmetic (the body count continues!) than movies.

One Christmas Eve, Billy's parents take him to visit grandpa in the mental asylum, where the loony old cuss tells the boy that Santa will punish him if he's been naughty. Sure enough, when the parents stop by the side of the road to help a Santa in distress, Jolly Saint Nick shoots the father, rapes and slashes the mother. Billy grows up in an orphanage run by a sadistic mother superior who ties him to his bed, and whips him with a heavy leather belt when he stumbles on two orphanage staffers mortally sinning in the stockroom. Worse, she forces him to sit in Santa's lap -- for Billy, the lap of the man who murdered his parents.

Fa la la la la, la la la la!

This could be goofy fun, but it all plays like a psych textbook from Hollywood U. Billy is emotionally scarred, inculcated with guilt (first by the grandfather, then by the nuns). So naturally, when he graduates from the orphanage school and is given the chance to play Santa in a toy store, he enters the role with a vengeance. Armed variously with a noose of Christmas lights, a razor, a claw hammer, a bow and arrow and an ax, he decks the halls with gore. Only one little girl escapes his wrath; when she assures him she hasn't been naughty all year, Santa tenderly hands over his blood-stained razor. When you can't say it with words . . .

The special makeup effects are amateurish; and Sellier has composed the movie almost as a set of still photographs. The fresh-faced Robert Brian Wilson brings no hint of the sinister to the killer -- lurching around in his Santa suit, he just looks like Darren trapped in one of Samantha's nuttier schemes. The movie follows the generic splatter formula: kids have sex, and the monster, muttering "Punish! Punish!," teaches them a lesson. You'd expect a more unique style of villainy from Kris Kringle -- it's just a short cut to shocking you. He might as well be the Easter Bunny.

Hack-'em-ups like "Silent Night, Deadly Night" are structured like pornography, a series of set pieces, each of which provides a different thrill. But there's nothing thrilling anymore about seeing someone with a hammer embedded in his skull, or shredded through a broken window, or decapitated while he rides a sled. As you realize that you've sat in the same theater and seen the same things every Friday the 13th, the walls begin to close in on you -- it's a kind of Claustrophobia.

"Silent Night, Deadly Night," now playing at area theaters, is rated R for graphic violence and nudity.