“The Vigil” is the most original, most chilling horror film of the new year. And let me hasten to add, it’s not even close.

It’s a supernatural thriller set in an Orthodox Jewish community of New York, which is novelty enough. But first-time writer-director Keith Thomas builds on what recent documentaries have shown us about the struggles of men and women who want to escape such rigid, insular, patriarchal and punitive groups, films such as “Unorthodox” and “One of Us.”

That’s how we meet Yakov (Dave Davis), in a support group of fellow “ex-Orthodox,” struggling to do manage the simple business of living and finding work in big, bad New York after disconnecting from a society where much of that was taken care of by the theocratic elders.

He is being stalked by his former rabbi (Menashe Lustig), not that Reb Shulem sees it that way. He waits under a street lamp and just “wants to ask a question.”

The rabbi has an offer of work that he wraps in words of concern and gently-badgering recruitment to return to the fold. Sure, whatever. What’s the job?

Be a shomer for the night. Sit with a recently-deceased recluse, recite Psalms, “protect” the body from “an unseen evil,” the opening titles of the film informed us are the meaning of the tradition.

The dead man had a shomer, “but he just ran out.”

After haggling over the midnight to dawn fee, Yakov agrees. The meeting with the slightly-demented widow (Lynn Cohen) doesn’t go well, despite reassurances that “she’ll likely sleep through the night…It’ll be quiet.” But a deal’s a deal.

As Yakov pops in his earbuds and fiddles with this new smartphone gadget, Googling “How to talk to women,” we get the distinct impression that he’s not taking this “holy” but creepy duty seriously. The ominous brass in the score and the metallic thunks and bumps behind the walls and ceiling, the “whoosh” sounds around him tell us that’s not the smart play.

The conventional but clever plot is familiar to anybody raised on Indiana Jones. Take religious tradition, especially Old Testament rituals, too lightly, and there’ll be Hell to pay.

Just as predictable is the thing we just know is Yakov’s best hope of surviving the night, the very thing he fled.

But Thomas weaves in genuinely chilly moments and background details that take “The Vigil” from interesting to riveting. They include the support group’s unworldly naivete and thinly-veiled contempt for the “goyim” they’re having to deal with now, Yakov’s troubled personal history and the film’s framing device.

The story opens on a grim, grey day in hazy soft focus — a pistol pointed at a head, an SS lapel badge in view. The dead man survived the Holocaust. Now his body is under threat again.

Thomas locks in the viewer with a mystery we must unravel, traditions and rituals we ponder. He stumbles into over-explaining, a single scene that dissipates too much of “the unknown.”

But that doesn’t wholly break the spell of “The Vigil,” a most unusual twist on demonic possession and the benchmark movie for the horror films of 2021. See if you can top this.

MPA Rating: PG-13 for terror, some disturbing/violent images, thematic elements and brief strong language

Cast: Dave Davis, Menashe Lustig, Malky Goldman and Lynn Cohen

Credits: Scripted and directed by Keith Thomas. An IFC Midnight release.

Running time: 1:29