“Old” begins as mysterious, creepy and filled with the foreboding — that sense that some “gotcha” is coming — that is M. Night Shyamalan’s brand.

Immaculate camera compositions, a beautiful but forbidding isolated beach location in a digitally-augmented Dominican Republic maintain the edgy and elegiac mood of this sci-fi fantasy meditation on aging.

Well, that’s what it aims to be, right up to the most laughably clumsy “explainer” of a third act that Shyamalan has ever served up.

“Old,” adapted from a French graphic novel, has a “Six Characters in Search of an Author” (Pirandello) or “Five Characters in Search of an Exit” (Serling) set-up. As our disparate collection of strangers — eight adults and three children — struggle with the supernatural trap they find themselves in, we see their characters and their weaknesses, physical and mental.

And little by little, they lose pieces of the lives they’ve lived and the bodies they’ve enjoyed. Their world and their experience of it shrinks and is overwhelmed with loss. Because that’s what getting “old” does to you.

Our anchor family is the married couple Prisca (Vicky Krieps of “The Last Vermeer” and “Phantom Thread”) and insurance actuarial Guy (Gael Garcia Bernal), their precocious six-year old son Trent (Nolan River) and tweenage daughter Maddox (Alexa Swinton). Prisca, a historical museum curator, found this “version of paradise” resort on the Internet.

As a little something extra, they’re dropped off at this remote, almost inaccessible beach by a not-helpful-enough driver (M. Night’s cameo). Another couple, a surgeon (Rufus Sewell) and his self-aware trophy wife (Abby Lee), his elderly mother and their tiny daughter, are with them.

And they’re joined by another couple — psychotherapist Patricia (Nikki Amuka-Bird) and her nurse-husband Jiran (Ken Leung).

The man who was already there when they all arrived, brooding in the shade of the cliff? Young Maddox IDs him as Mid-Sized Sedan Aaron Pierre), a rapper.

When the skinny-dipping blonde who came with Me. Sedan to this beach turns up as a floating corpse, their idyll is interrupted. And just as the doctor is revealing himself as paranoid, actuary Guy is calculating the “odds” of the accident that must have killed her and everybody is figuring out that there’s no cell service here, Prisca shouts “Could you take a look at my son?”

Her boy has aged…years. Her daughter is busting out of her tween swimsuit. And when anyone tries to dash out to call for help, they black out. Someone or something is keeping them here, and days are passing in seconds, years in a matter of hours.

The veteran Brit Sewell (last seen in “Judy” and “The Father” and “The Man in the High Castle”) always makes a good villain, Bernal (“The Motorcycle Diaries”) shows off his vulnerability and Krieps impresses as a wife trying to adjust to an alarming new reality in the middle of an old reality that was about to tear her world apart.

There are semi-intentional laughs as the three children age into their hormonal years (Alex Wolff, Thomasin McKenzie and Eliza Scanlan step in the roles), but Shyamalan (“Sixth Sense,” Signs,” “The Village”) does a good job of keeping the viewer in the moment, not leaving much dead time for us to ponder just what the hell it is we’re witnessing here.

And then he has to go and “explain” it all, breaking the spell and ruining the illusion, the elegy and any sense of profundity that this thriller with horrific touches has the pretense to aspire to.

MPA Rating: PG-13 for strong violence, disturbing images, suggestive content, partial nudity and brief strong language

Cast: Gael Garcia Bernal, Thomasin McKenzie, Vicky Krieps, Rufus Sewell, Nikki Amuka-Bird, Ken Leung, Abby Lee, Aaron Pierre, Embeth Davidtz, Francesca Eastwood and Alex Wolff

Credits: Scripted and directed by M. Night Shyamalan, based on a graphic novel by Pierre-Oscar Lévy and Frederick Peeters A Universal release.

Running time: 1:48