Well, this probably seemed like a slam dunk movie pitch. Channel Allison Janney’s not-taking-your-s–t energy into a sort of “Gloria” meets “Hard Rain” thriller.

But as the action tropes quickly devolve into cliches and the hard-bitten dialogue lapses into a parade of eye-rollers, “Lou” — the movie, and the character named after her — loses her mojo.

Lou is a loner, living on a remote island in the Pacific northwest with her trusty cattle dog, Jax. She’s a known quantity to the locals, stalking with purpose from errand to errand, not wasting energy or words, not suffering the rude, the unreliable or strangers gladly.

As a bad storm’s rolling in, she’s tempted to say something soft and supportive to single mom Hannah (Jurnee Smollett), who’s renting a trailer from her. But Hannah’s late on the rent, and stern Lou is easier than the effort it takes to be sweet Lou, so nothing doing.

Lou’s got money buried in a box on her property. She’s handy with a rifle, and a gutting knife. And as she burns old photos, film and partially-redacted “Dept. of State” papers in the fire, we start to piece together who she was.

Her wincing at Reagan lying on national TV almost finishes the picture. It’s the ’80s, and the note she’s writing for whoever finds her as she rehearses how the rifle will fit right below her chin cinches it.

“I left the world a more dangerous place than I found it.”

As the storm pounds in, Hannah rushes in to use her phone — suicidus interruptus. Somebody’s grabbed her pre-schooler, Vee (Ridley Asha Bateman), somebody serious enough to kill a mutual friend to get to her.

“Turns out I’m not done yet,” Lou mutters to Jax the dog as she springs into action.

Turns out Hannah’s “dead” ex (Logan Marshall-Green) has snatched her. Inexplicably, he’s brought a “team” to carry this out. But as this is staged on an island, they can’t get away clean while there’s a storm going on. Lou, with Hannah tagging along, is dogged set on “tracking” them.

“There’s no ‘help’ coming! I’m all you’ve got!”

Janney does “mean” so well that we don’t spend a lot of time dwelling on the 60something woman pummeling, stabbing and out-punching assorted ex-military chaps that are much stronger and younger and hellbent on getting away with this little girl. A bit of an eye-roller, but so’s Eastwood, throwing punches into his ’70s and ’80s.

What’s grating is the way Hannah starts running down the resume of her murderously dangerous, disgraced ex-Green Beret husband. Yes, exposition is often handled this way — in bad B-movies.

Lou hands Hannah the rifle and asks ” You know how to use this?” when the viewer can guess the answer. Lou gives her a knife — “Go for the eyes. A man can’t kill what he can’t see.”

And you think, “All this to steal a child? What’s really going on here?”

Janney is flinty enough in what isn’t one of her best performances. Smollett, recently seen in “Lovecraft Country,” but a reliable screen presence since “Eve’s Bayou,” gives the picture its heart.

But “Lou” turns out to be one of those “once in a century storm” movies that um, forgets the storm. The story staggers from assorted body blows, and teeters over into nonsense as the pieces in the ditzy puzzle supposedly fall together, this after the action beats — a rope bridge, “the lighthouse” — start to feel like cut and paste items from a multiple choice thriller template you find online.

“It’s a trap!”

Yes. Yes it is.

Did you miss “Lou” when Netlix released it on late Sept? Turns out, you should have.

Rating: R, Violence and profanity

Cast: Allison Janney, Jurnee Smollet, Ridley Asha Bateman, Matt Craven, Logan Marshall-Green

Credits: Directed by Anna Foerster, scripted by Maggie Cohn. A Netflix release.

Running time: 1:47