It isn’t scary, with even the best-engineered “gotchas” landing flat. Kind of a big deal when you’re making a horror film.

It’s joyless and humorless to boot, with slick production design that imagines a creature-inhabited “forest” on an island generally forest-free (but not around Wicklow) — Ireland.

“The Watchers,” adapted from a novel by Irish writer A.M. Shine, stumbles onto the screen under a “nepo baby” cloud, with miss-or-hit horror impressario M. Night Shyamalan’s daughter Ishana Shyamalan as writer-director. The best one can say for her hand here is that she’s competent and utterly uninspired.

M. Night, long one of our more delightfully egomaniacal cinematic self-promoters, must have figured that he could turn his “brand” into a filmmaking dynasty.

Nope.

But at least that spares poor Dakota Fanning much of the beating this derivative drivel richly deserves. One of the least expressive actresses of her generation, she plays an American pet shop clerk ordered to deliver a talking yellow parrot (Perhaps a Golden Conure?) from Galway to Belfast, only to break down in a vast forest from which “there is no escape.”

Our clerk, Mina, stumbles into this sage older woman, Madeleine (Olwen Fouéré) who lets her into “The Coop,” a bunker-like structure where Madeleine, Ciara (Georgina Campbell) and young Daniel of (Oliver Finnegan) are holed up.

They have been here for varying lengths of time. Those who tried to escape were never heard from again. So they have to trap and kill their own food, they tell her — ravens or crows, mostly. They cannot be out after sunset. They must “never” look into the burrows that honeycomb the forest. And despite a lot of “Point of No Return” signs that ostensibly could guide someone out, they can’t make it all the way out before darkness comes.

Thus the trap. And every night, “The Watchers” insist they stand up in front of the mirror facing a window and be displayed to their captors.

“It is not wise to keep them waiting.”

The dialogue is a collection of mytho-poetic rubbish of the “It is said that they once walked among us” explanations. The set decorations include an ancient CRT TV and DVD player and an even more ancient Victrola.

We and Mina hear the rules. We and Mina see flashes of children — hallucinations — in the forest. We pick up on Mina’s past, why she’s exiled herself to Ireland.

And not a word of it, not a single fact forced-in, not an attempted “escape” or breach of “The Rules” can do a damned thing to interrupt the tedium.

Bringing in John Lynch for further third act explanations has a “too little, too late” and “Too much” explaining about it.

I’m inclined to think the clumsy and cumbersome material itself, being M. Night “adjacent” in themes and set-up (“Knock at the Cabin”), is just not worth the trouble of adapting.

But Ms. Shyamalan and Ms. Fanning seal its fate, each in her own way — one for having no “gift” or flair for directing, and for casting Fanning and the other for not knowing better — at 30 — than to accept a part that required more of her than she’s got in her repertoire.

Rating: PG-13, some nudity, bloody violence, profanity

Cast: Dakota Fanning, Georgina Campbell, Olwen Fouéré, Oliver Finnegan and John Lynch.

Credits: Scripted and directed by Ishana Shyamalan, based on the novel by A.M. Shine. A New Line release.

Running time: 1:41