“Doorbusters” is possibly the most odious term of the modern holiday season, and this comic horror movie opens with a slo-mo shot of one of these sales: Shoppers trample one another and fight over cheap toys, set to a cheery carol. Seeing as “Krampus” is about the Alpine demon who punishes Christmas a-holes, this is a promising start — but alas, it’s all downhill from there, making a murky and humorless hash out of a pretty great piece of folklore.
Max (Emjay Anthony), a boy on the cusp of not believing in St. Nick anymore, is exasperated with his boorish visiting relatives (Allison Tolman, David Koechner, Conchata Ferrell) and his checked-out parents (Adam Scott, Toni Collette), leading him to rip up his letter to Santa and fling it out the window, where it summons Krampus — “Santa’s shadow” — to wreak havoc.
A howling blizzard descends, and director Michael Dougherty sets most of the haphazard action in either swirling snow or relentlessly blinking holiday light, so good luck figuring out what’s going on. Squinting, I could make out a giant horned figure — that’d be Krampus — and his minions, including goblinlike gingerbread cookies and a gang of nightmarish toys.
More problematic is the human element: This very capable cast has absolutely no wit to work with in a screenplay co-written by Dougherty. “It looks like Martha Stewart threw up in here,” Max’s boozy aunt (Ferrell) observes of the house décor — and that’s about as funny as it gets. Meanwhile, Tolman and Koechner play parents of kids who are supposedly amusing because A) the boy is chubby and B) the girls don’t dress girly enough (the equally icky explanation: not that they’re tomboys, but that their dad wishes they were boys.)
The moral of the story — I guess? — is be careful not to resent your irritating relatives during the holidays, or else. It’s a tall order: That’s an American tradition right up there with prepackaged eggnog, mall Santas, and doorbustin’.