Watching the movie version of the Broadway musical “Cats,” I’m sure I had the same look on my face that I get when I watch my own two cats, Angel and Gracie, prowling around my house: a bemused bewilderment as my brain forms the question, “What the hell are they doing?”

I know Andrew Lloyd Webber’s stage musical, adapting a book of whimsical poems by T.S. Eliot, has been wildly popular ever since it debuted in London in 1981, and had a 21-year run on Broadway — a record at the time, now held by Lloyd Webber’s “The Phantom of the Opera.” What I didn’t know is what a formless blob it is, a jumble of musical numbers devoid of plot and pacing, and director Tom Hooper, who last corralled “Les Miserables” to the screen, can do nothing to change that.

What passes for a story in “Cats” is this: A recently abandoned kitten, Victoria (ballerina Francesca Hayward, in her screen debut), falls in with a community of alley cats near London’s Egyptian Theatre. She learns that this night is special, because it’s when the Jellicle Ball takes place. All the cats are “jellicle” cats, with “jellicle” quickly becoming the most overused nonsense adjective since “smurfy.”

At the Jellicle Ball, the cats’ leader, Old Deuteronomy (played by Dame Judi Dench), will choose which cat will get to go to a new life in the Heaviside Layer — which, we learn in context, is the cat version of heaven. Each cat in competition will sing a song about themselves, explaining who they are and why they deserve the prize. This is all well and good, if one doesn’t dwell on the fact that the prize is death.

Among the contestants the musical introduces us to are: the pampered Jennyanydots (Rebel Wilson), the Lothario Rum Tum Tugger (Jason Derulo), garbage can connoisseur Bustopher Jones (James Corden), cat burglars Mungojerrie (Danny Collins) and Rumpleteazer (Naoimh Morgan), Gus the Theater Cat (Sir Ian McKellen), the railway cat Skimbleshanks (Steven McRae) and the magical Mr. Mistoffelees (Laurie Davidson).

An interloper to the ball is Macavity, the elusive “Napoleon of crime,” who wants to win the Jellicle Ball and will cheat to do so. Macavity is played by Idris Elba, though he doesn’t sing very much; he has a hype-cat, Bombalurina, played by Taylor Swift.

In the fringes, shunned by the other cats, is Grizabella (Jennifer Hudson), a former beauty — a “glamour cat,” the others call her — who has fallen on hard times. Victoria tries to draw her out with kindness, and Grizabella responds by singing about her past glories in the movie’s most well-known showstopper, “Memory.”

Hooper, co-writing the screenplay with Lee Hall (“Rocketman”), can do little but string these cats’ numbers along a threadbare clothesline of a plot, which borrows more than a bit of imagery from “The Wizard of Oz” and “The Borrowers.”

Each number must stand or fall on its own merits, with McKellen’s shambling recollection of his stage triumphs, Swift’s account of “Macavity, the Mystery Cat” and Hudson’s belting of “Memory” leading the way. On the other hand, Old Deuteronomy’s to-the-audience lecture on “The Ad-Dressing of Cats” and the Swift/Webber-penned new song, “Beautiful Ghosts,” are snoozers — and Corden’s and Wilson’s solos are just plain odd.

Odd doesn’t begin to describe Hooper’s choice of using computer-animated motion capture technology to give the cats their fur. Where many stage productions put the cast in body suits with cat faces and furry leg warmers to suggest the feline look, here the faces are quite human — as are the bodies, though covered in computer-generated fur from head to toe. It’s quite elegant for Hayward and her fellow dancers, lithely moving to the music, and helpful to Elba to add muscular menace to Macavity. For other characters, the look is inconsistent and awkwardly covered up with costumes.

Conjuring up the visuals of this weird world — the cats’ relation to the human London, from Piccadilly Circus to Nelson’s column, is never adequately explored — can’t hide a script that’s more plot hole than plot. Surely fans of “Cats” in its many staged iterations will love this movie just as much, but don’t expect the rest of us strays to jump in the sandbox.

★★1/2
‘Cats’
Andrew Lloyd Webber’s plotless musical about our feline friends is the basis for a bizarre headscratcher of a movie.
Where • Theaters everywhere
When • Opens Friday, Dec. 20
Rated • PG for some rude and suggestive behavior.
Running time • 110 minutes