What a salacious and silly miscalculation “Miller’s Girl” turns out to be.

It’s neither ridiculous enough to be a fiasco, nor laugh-out loud off-key. But “off” it most certainly is — off-the-wall and off-putting.

First-time writer-director Jade Halley Bartlett’s script sounds like a grad student’s attempt to imitate Tennessee Williams trying to adapt Henry Miller’s version of David Mamet’s “Lolita.”

Sorry. English Major’s joke.

The florid, literary fiction turns of phrase that come out of teenager’s mouthes here would fill an issue of “The Southern Review.” But in many states, they’d have to sell it behind the counter in a brown paper wrapper — like “Penthouse” in the porn-leery ’80s. It’s a bit “blue” as we used to say. Not titillating. Just dirty-talked to death.

And Jenna Ortega, “It” girl of TV’s “Wednesday” and horror icon of the recent “Scream” revival, finds herself reduced to a hyper-sexualized child, because apparently she wanted to get that off her bucket list before she was too old to pull it off.

Raw, luridly risible lines ripple out teenager Cairo (Ortega), which her favorite lit/creative writing teacher Mr. Miller (Martin Freeman, who should know better) just eats up.Even her insults.

“No one will pay more thought to you than they would an unread fortune cookie.”

He’s a failed writer in “BFE” Tennessee, trying to convince his “trust fund baby” star student to apply to Vanderbilt when she has Yale where Miller insists they “eat pot brownies and read Joan Didion” on the radar. But college entrance essays about “major accomplishments” in her teen life have her troubled.

Artist wild-child pal Winnie (nepo baby Gideon Adlon) suggests losing their virginity using an older “man to take me to pleasure town.” She has her eye on the Coach Filmore (Bashir Salahuddin). After all, “Older men have been harvesting virginity since the dawn of time.”

And by the way, Winnie’s “never seen (Mr. Miller) look at a student the way he looks at you.”

Whatever Winnie’s “sexual ambivalence,” Cairo is intrigued by this “major accomplishment” possibility as a writer’s milepost, if not something she’d write about on an admissions exam. As she has the wardrobe, bedroom eyes and mature vocabulary to make this happen, she sets events in motion.

Jon Miller is a failed writer whose “fallback” career is in public education. At least the kids and his pal, Coach Filmore (Who also teaches physics!) are sweet enough to nickname him “Professor.”

Miller’s married to a tipsy, Tennessee Williams cliche. Bea (Dagmara Dominczyk) staggered straight off the set of “Night of the Iguana,” a voluptuous alcoholic who writes and lounges about in black bras and negligees.

She is not shy about her needs, and unfiltered if not unkind about the disappointment Jon turned out to be.

“You chose to be a teacher,” she offers. “You married a writer,” he snaps.

When Cairo turns on the eye contact and violates his personal space, he notices. When she chooses as her final exam writing project an R-rated homage to “Tropic of Cancer” novelist Henry Miller that barely disguises her lust for her teacher, he blushes.

“If it’s not controversial, it’s not interesting,” she purrs.

Is it too late to back out before he’s trapped and fired and book-banning Tennessee has him burned at the stake?

First-time writer-director Bartlett has her production designer overdecorate Mr. Miller’s classroom and a Victorian Village (Memphis) poetry slam with gaudy lamps that look like props from an antique store production of “The Glass Menagerie.”

She dresses Ortega in miniskirts and leggings or boots, or tony/sexy evening wear more appropriate for a magazine cover than a high school kid’s wardrobe.

Her script has Cairo deconstruct her own work with every literary criticism cliche in the book, and launch into a long, purple passage from Mr. Miller’s lone published novel. quoted from memory. And Mr. Miller quotes one of Cairo’s short stories back to her via eidetic memory in a mix of awe, envy and sexual heat.

As even the diminutive Freeman towers over the petite Ortega, their “sexual” tension moments peg the “ick” needle. He’s a high-mileage, white-haired late 40something and she’s not looked this young in years. We don’t buy in. And not just because his attempted accent comes and goes and she never bothers with one.

Adlon, daughter of Pamela, gives us the story’s youthful vulnerability. Any sexual predation Winnie talks up is plainly a pose, part of Winnie’s ongoing search for her sexual self. But call her bluff and she’s the one true child here.

Domincyk of TV’s “Succession” devours her scenes and her co-stars, pretty much channeling Ava Gardner as she does. It’s the film’s most over-the-top turn, suggesting she’s the only one in on the joke.

As Lionsgate didn’t so much “release” this unsettling misfire as allow it to sneak out the back door in the dumping ground of January, hopefully one and all can put it behind them and pray no one remembers it a year from now.

But bad decisions are telling, and while Freeman is in a take-what-I-can-get stage of his career, it is Ortega who should be second-guessing the entire process that put someone as in-demand as she is in this picture with this green and misguided writer-director.

Whatever Ortega thought playing “Miller’s Girl” might do for her post “Wednesday” and “Scream” image, nothing good came from it. Just embarrassment for her.

Rating: R, sexual situations, teen drinking and smoking, profanity

Cast: Martin Freeman, Jenna Ortega, Dagmara Dominczyk, Bashir Salahuddin and Gideon Adlon

Credits: Scripted and directed by Jade Halley Bartlett. A Lionsgate release.

Running time: 1:33