You know you’re movie is in trouble when you’re secondary characters are infinitely more interesting and charismatic than your two leads. Such is the case with “Fantastic Beasts and Where to Find Them,” the long awaited “Harry Potter” spinoff in which series creator J.K. Rowling makes her not-so-magical screenwriting debut.

It stars Oscar-winner Eddie Redmayne and “Inherent Vice” ingenue Katherine (daughter of Sam) Waterston as a sort of de facto Harry and Hermione flitting about a dark-and-dour Manhattan during the Jazz Age trying to … I’m not exactly sure what. It has something to do with wrangling a menagerie of magical beasts that have escaped Redmayne’s equally magical valise, but leads only to yet another tiresome cameo by Johnny Depp. What transpires between feels more like “Batman v Superman,” as expository dialogue and crumbling mortar try to pass themselves off as entertainment.

The lone bright spots are Dan Fogler and singer-songwriter Alison Sudol as the “comic-relief sidekicks” of Redmayne’s “magizoologist” Newt Scamander and Waterston’s peace-officer Porpentina Goldstein. Fogler, an adorable, roly-poly wannabe doughnut-maker, and Sudol, a mind-reading vamp channeling Clara Bow and Mae West, are a never-ending wellspring of delight with their forbidden flirtations. They’re also the lone source of pathos because their budding romance can never be by virtue of Fogler’s Jacob Kowalski being a muggle, or “no-maj” (short for no magic) as they say in the States, and Sudol’s Queenie being of the hocus-pocus persuasion. She’s also the sister of Porpentina, who has no use for muggles, particularly with a witch hunt going on outside that’s billed as “the second Salem.” Kudos to Rowling for foreseeing the us-against-them paranoia currently sweeping the U.S. It fits nicely into what we see happening in the streets of New York, circa 1926. But that’s where the relevancy of her script, written in 2013, begins and ends. Unlike Steve Kloves, who penned seven of the eight “Potter” scripts, Rowling has no grasp of screenwriting. Her characters are flat and underdeveloped, her plotting scattershot and her action scenes tired and derivative. It’s boring, and — except for Fogler and Sudol — utterly lacking in joy and warmth.

Even the strange creatures that spring from Newt’s suitcase lack imagination. Putting wings on a snake? Really? That’s the best you can do? I’ve also never been a big fan of David Yates, who directed the last four “Potter” movies and is back in the saddle here. He’s steady and competent, but his movie lacks energy, not to mention a sense of purpose beyond bleeding the pockets of parents looking for something to occupy their little muggles.

Then there’s Redmayne, amazing as Stephen Hawking in “The Theory of Everything” and annoying in the overrated “The Danish Girl.” Here, he’s more of the latter, doing something bordering on a drippy Hugh Grant impersonation, sans the charisma. He even has the same floppy hair Grant wore in “Three Weddings and a Funeral.” But, sir, you’re no Hugh Grant. You’re pretty much a non-descript cypher, far from the magic man your Newt is supposed to be. As for Waterston, she’s so bland it’s hard to believe she’s the same actress who played the sexy, seductive hippie who charmed the pants off of Joaquin Phoenix in “Inherent Vice.” As a couple she and Redmayne make “Fantastic Beasts” a drudge, saved only intermittently by Fogler and Subol, who seem to be the only actors having fun. We certainly don’t see it from Colin Farrell as the head of the magic gestapo, or Jon Voight, wasted in a nothing role as a newspaper mogul trying to get his hapless son elected to Congress. The hope is that all of these characters will evolve in what’s rumored to be four sequels, but I just don’t see it happening. Unlike the “Potter” franchise, which benefitted from cute kids, intriguing mysteries, adolescent hormones and an overall British-ness that befit it, “Beasts” looks like it’s going to be a chore. But then, what do I know? I’m only a muggle.

“Fantastic Beasts and Where To Find Them”
Cast includes Eddie Redmayne, Katherine Waterston, Alison Sudol, Dan Fogler, Colin Farrell, Jon Voight and Ezra Miller.
(PG-13 for fantasy action sequences.)
Grade: C-