By Lynn Venhaus
Half-baked and bogged down by subtext, the high concept “Old” fritters away its intriguing potential by dispensing too little explanation in its trouble-in-paradise vacation plot.

A dream vacation turns into a nightmare for tourists at a luxury resort, who start out spending the day at a secluded private beach, but a mysterious and sinister force results in rapid aging, reducing their lives to the remaining hours in the day as they race against time.

And, despite a good cast, the everything-but-the-kitchen-sink story winds up a tedious exercise heavily borrowing from Agatha Christie’s “And Then There Were None” – that age-old chestnut in which a group of people are thrown together at a remote location, but are somehow connected, and the corpse count piles up.

As he is known to do, writer-director M. Night Shyamalan bends time and logic to suit a story about medical testing with tragic results — all for the greater good. Shades of pandemic paranoia!

With his penchant for riddles and games, Shyamalan features some interesting developments — and of course, delivers his patented “twist,” but in the meantime, one can be distracted by things that do not make sense, even for a sci-fi-laced adventure.

However, the script is not an original one, for it is based on a Belgian-Italian graphic novel called “Sandcastle” by Pierre-Oscar Levy and Frederick Peeters.

Ever since the post-atomic age films, starting in the 1950s, mad scientists and unscrupulous doctors have been part of the cinematic landscape. And a luxury resort, with its flip on “The Love Boat” genre, provides both lush and mysterious landscapes.  Cinematographer Mike Gioulakis captures the beauty and the foreboding elements while overwrought music score by Trevor Gureckis swells.

Eleven characters are enjoying fun in the sun when a young woman’s body is found floating in the water (Francesca Eastwood as Madrid). Then, the parents notice their children appear older– their growth acceleration is alarming, and various actors take on the roles of Trent, at first a precocious 6-year-old, and Maddox, 11, when the journey begins, the children of Guy (Gael Garcia Bernal) and Prisca (Vicky Krieps).

Alex Wolff and Thomasin McKenzie play the older teenage siblings. Eliza Scanlen, Beth in Greta Gerwig’s “Little Women,” is the 15-year-old Kara, the daughter of Charles (Rufus Sewell) and Chrystal (Abbey Lee). Their sexual maturation is a tad disconcerting, given the ‘hours’ in the day, as well.

Tensions escalate as the group is at a loss for what’s happening. If this were an episode of “Survivor,” this tribe would have voted the arrogant and unstable doctor, played by Sewell off the island first.

Unfortunately, these characters are all one-note, for there isn’t time to shade them with more nuance. Aaron Pierre plays rapper Mid-Size Sedan, who is looked upon with suspicion by Charles in one of the uglier subplots.

The characters who enter a cave have their heads hurt – but that isn’t explained, and is it symptomatic of what’s taking place? Not sure what’s being pulled here by the characters playing God.

The standard “problems in our marriage” is heavily used and is tiresome, especially with little backstory. Bernal, who hasn’t followed his performance as Che Guevera in 2004’s “The Motorcycle Diaries” with anything on that level film-wise, although was terrific in “Mozart in the Jungle,” disappears into the bland patriarch role. He has little chemistry with Krieps, whose “Phantom Thread” performance was outstanding, even if they are playing a mom-and-dad on the rocks.

Good supporting work is by Ken Leung, who was in the time-twister series “Lost,” as compassionate nurse Jarin, who is married to Patricia, a therapist with epilepsy, well-played by Nikki Amuka-Bird. She is eager for the group to talk it out, but she is largely ignored, as assumptions and rash decisions increase.

We are on a collision course on this death train, and that’s just the way these horrific adventures go for those trapped in isolated surroundings.

Some of the deaths are particularly gruesome, and the camera lingers excessively on a few inevitable demises, with Brett M. Reed the on-the-nose editor. Why do some cuts heal and some don’t? If you value consistency, even in a horror movie, you will be scratching your head.

There is a better movie hidden in this somewhere. While Alfred Hitchcock didn’t hit it out of the park every film, we should expect a well-constructed story if you are goi g to emulate the master of suspense. You don’t need a film scholar to lecture you on what happens and why – it should be obvious.

Shyamalan, who wowed audiences with 1998’s “The Sixth Sense,” but has been hit-or-miss ever since (and I say this as a fan of “Unbreakable,” “Signs,” “The Visit,” “Split” and yes, even the derided “The Village”), will always be worth a look.

While not entirely unwatchable, “Old” is not the satisfying yarn I had hoped it would be.

Oh, and that Jack Nicholson and Marlon Brando movie that Charles can’t remember is “The Missouri Breaks.”

“Old” is a 2021 sci-fi thriller directed by M. Night Shyamalan and starring Gael Garcia Bernal, Vicky Krieps, Rufus Sewell, Abbey Lee, Alex Wolff, Thomasin McKenzie, Eliza Scanlen and Aaron Pierre. Rated PG-13 for strong violence, disturbing images, suggestive content, partial nudity and brief strong language, its run time is 1 hour, 48 minutes. Available in theaters on July 23. Lynn’s Grade: C-.