As Advent is now upon us — the original Catholic countdown to Christmas before America invented “Shopping Days” to keep better track — this is the perfect season to unleash a horror movie about an evil artifact attached to this holiday.

Hey, nobody even MENTIONED Elf-on-a-shelf.

“The Advent Calendar” is a creeper of a thriller. It stalks you, sidles up and immerses the viewer in its world and its mood. This Belgian film (in French and German with English subtitles) doesn’t deliver frights or shocks so much as it serves up shivers.

Actor turned writer-director Patrick Ridremont’s clockwork screenplay presents a chilly artifact — the 24 day wall-hanging calendar with key-locked “doors” for each of the days approaching Christmas. And it gives us “rules.”

The movie is “The Ring” or “Ouija” with a Christian calendar that dispenses candies behind each day’s potentially deadly door.

Eugénie Derouand plays Eva, a poker-faced beauty who gets hit-on in the public swimming pool, right up to the moment she crawls into her wheelchair. She used to be a dancer, now she’s paraplegic.

We meet her on her birthday, get a taste of her solitary life (she lives with her dog) and work (selling insurance).

She’d love to talk to her father (Jean-François Garreaud) on her special day. But he’s deep into dementia, and his shrew of a second wife (Isabelle Tanakil) has no interest in nurturing that relationship. Like Eva’s crude and unfiltered boss (Jérôme Paquatte), Evil Stepmom can’t be bothered to filter her insensitive language when talking to or about Eva’s “condition.”

Not to worry. As Eva’s birthday coincides with the start of Advent, her bestie Sophie (Honorine Magnier) hot-to-trots her way back from Germany with a special gift — a wooden Advent calendar.

It’s got a threat wood-burned into the back. “Dump me, and I’ll kill you.” And there are other “rules.” Behind each date-door, there’s a candy. “Eat one candy, you eat them all.” Fail to do this? “I’ll kill you.”

As the calendar is from Germany, these operating instructions/threats are delivered in German, which Sophie reads and speaks.

“Ich bring dich um” sounds “pretty grim.”

“Germans are grim!”

As Eva likes the type of candy in the first compartment — it’s her father’s favorite — she buys in. Later that day, she gets a pleasant, short birthday call from her father.

Wait. What? Was the candy drugged? “Are you still taking your anti-hallucination pills?”

Eva picks up on what’s happening quicker than Sophie or anyone else. She eats this candy, thinking of her Dad, and he experiences a flash of sentience. Eat that one that comes with the card that says “To cure hurt, destroy what hurt you” and something more sinister is in store.

What can that mean? Well, for one thing, that creep who sexually assaulted her while giving her a lift home from the club had better listen when Eva screams “Drop DEAD!” as he dumps her and her wheelchair into the street.

One of the clever touches in Ridremont’s “24 Days of Death” script is the calendar itself. A disembodied German voice speaks from inside it, a pop-up of a crucifix-wearing monk that appears after something has happened appears to be the mysterious threatening “Ich” or “I.”

And when boorish, brutish Boris tosses Eva from his Mercedes, a toy G-Wagon rolls out of one of the doors, and Martin, Eva’s dog, sees it and figures its a new chew toy. Whoa. Hate to be inside a “real” SUV while that was happening.

The malleability of the “rules” and the degrees of cleverness in the various ways the calendar “punishes” Eva, someone who wronged her or someone who loves her, puts fresh wrinkles in this somewhat conventionally-structured thriller.

The pace is seriously slack, providing time for Eva to be twisted by what she can see is going on, and to turn greedy at the possibilities that this magic talisman affords, but also hindering any chance the picture has in building suspense and horrific momentum.

“Advent” is more a puzzle with dire consequences than a vehicle for “GOTCHA” frights and grim and gory deaths. Although it provides a few of those, too, we don’t get scenes that allow us to develop empathy for anyone save for our “crippled” heroine and the “puzzle” is not something the picture provides us with enough information about to “solve” ourselves.

Derouand plays Eva as inexpressive, accepting insults and evidence of the supernatural almost unruffled. But as she starts piecing together this “puzzle,” and recognizes the stakes, the character turns more addled, frazzled and testy, making this gloomy tale of holiday “treats” a treat itself.

Rating: unrated, violence

Cast: Eugénie Derouand, Honorine Magnier, Cyril Garnier, Clément Olivieri, Janis Abrikh, Jérôme Paquatte and Jean-François Garreaud

Credits: Scripted and directed by Patrick Ridremont. A Universal production, a Shudder (Dec. 1) release.

Running time: 1:41