If someone told me in January that one of the funniest comedies of the year would be an R-rated movie about a hard-drinking Santa Claus, I would have laughed in their face.

But now … well, I believe.

“Violent Night” is for grownups only, with its gory but clever kills and sarcastic, jaded Santa (played wonderfully by David Harbour, of “Stranger Things” fame.)

We first see Santa in a London pub, where he’s drinking his woes away. He seems to be disenchanted with his career, even though he still has gifts to deliver on Christmas Eve.

Next, he ends up in a Connecticut mansion, where a vicious gang of thieves will stop at nothing to get their hands on the family’s loot.

Among the family members is an estranged couple (Alexis Louder and Alex Hassell) and their little girl (Leah Brady) who believes in Santa Claus and thinks maybe the jolly old elf will use his magic to get her parents back together. (She has, incidentally, just watched “Home Alone,” which will figure into the proceedings later in the film.)

The criminals are led by John Leguizamo’s “Mr. Scrooge,” who isn’t afraid to resort to violence to get what he wants.

And there’s poor Santa, caught in a battle of wits with the bad guys and determined to help the little girl who believes in him.

This is far more clever than I ever imagined it would be, even in it staging of blood-soaked violence.

One of the nice touches in casting is Beverly D’Angelo as the matriarch of the wealthy family  – you’ll recognize her from her role in “National Lampoon’s Christmas Vacation.”

Also, Santa has a pretty cool back story that I didn’t expect.

The action slows down only long enough for the audience to laugh more at its dark humor that’s aimed specifically toward grownups who like their comedy, and their Christmas movies, with an edge.

When you see it, I think you’ll believe, too.

3 ½ stars

Rated: R for foul language and graphic violence.

Running time: One hour and 41 minutes.

At Cinemark, Davenport; Regal, Moline; and Palms 10, Muscatine.

Watch the trailer here.