“Vox Lux” is “A Star is Born” for the bubblegum babies of pop.

Brady Corbet’s screen drama, presented as a quasi-operatic epic, begins with tragedy and the fluke that turns a survivor of that tragedy into a pop diva. The third act is a tour de force concert scene which checks another item off that mental list, “Is there nothing that Oscar winner Natalie Portman can’t do?

The prelude — a prologue, really — consists of a 1999 school shooting in New Brighton, Staten Island. That’s where 13 year old Celeste (Raffey Cassidy) settles in for music class, when a freshly-skinheaded classmate shows up with a semi-automatic weapon, a Ford Explorer loaded with a bomb and a grievance unspoken.

He pretty much wipes out the class, despite Celeste’s pleas that “You don’t have to do this.” They all know that. They all ignore it.

But Celeste survives, albeit with a bullet lodged in her spine and pain medication that she’ll be taking for life. Her grim recovery includes picking out tunes on a portable keyboard with older sister Eleanor (Stacy Martin).

When she’s well enough to attend a memorial service/vigil, Celeste performs her plaintive teen dirge to grief. The TV news crews there capture it, and a star is born.

The story settles on more familiar ground — getting a manager (Jude Law), staying in New York and traveling to Europe with only her sister as her chaperone, growing up entirely too fast, locking in with Swedish pop producers of the Britney Spears era Stockholm pop music factory, asserting herself and making the sorts of mistakes kids of that Britney/Timberlake/Xtina/Rhona and JC era made.

But Celeste was never on “The Mickey Mouse Club.” Her “hook,” her ticket of entry to fame, was tragedy. That gives her 14 year old gravitas.

Jennifer Ehle plays the image-managing record company publicist who sets her up with a choreographer and pushes “in store performances” and other ways to reach her audience. Her manager may say “Half the time, I forget you’re a kid,” but “The Publicist” (supporting characters are stock “types,” without names) gives her adult-to-adult candor.

“Before we go making a lot of plans together,” she says, let’s realize that stardom and an enduring career are long shots.

Celeste Montgomery, thanks to what’s she been through, realizes that. She and her rock of support, the allegedly goody-goody big sister Ellie, get what they can out of while the getting is good. An underage bender in Stockholm is the first of many.

The Musician (Michael Richardson), a metal guitar player, is Celeste’s first “adult” romance, with all that implies.

“You make the same sort of music the boy who attacked me listened to,” should be a turn off. It isn’t.

“Act II/Regenesis” is where Portman shows up, the jaded pop diva with a teen daughter of her own (Raffey Cassidy again) whom she’s letting her sister raise while Celeste records her “Vox Lux,” literally “the voice of light.”

Portman chews up a Staten Island accent as this not-quite-burned-out pop star, a 30something woman out to top her past with a lavish spectacle of a tour, one she’s launching with a day of press interviews, a press conference and a show in her hometown.

Except terrorists, wearing masks seen in Celeste’s first music video, have just shot up a Croatian beach.

“Vox Lux” is an odd amble through the peaks and valleys of a pop career, the bubble of isolation that one settles in, the personality that traps you — as you are, at that age — forever.

Willem Dafoe provides sardonic narration that gives us American history, Celeste’s history — “Her family was on the losing side of Reaganomics” — and the history of post-war Swedish pop. But that narration also provides context with bite, how “Celeste’s loss of innocence strangely mirrored the nation’s.” She is “prisoner of a gaudy and unlivable present” at 31.

Rarely is voice-over narration in a film more than a filmmaker’s crutch. Making it droll, as Corbet does, just makes that less obvious.

Portman lifts a fairly humdrum film with a performance built on life experience. She too, grew up too fast, was dealing with the press in her early teens, sexualized at 13 in “Leon: The Professional.” I know. I first interviewed her about that film in 1994.

As Celeste, she affects boredom, even at the most thoughtful questions she’s asked. She bristles at any connection to the Croatian shooting and embraces her past victimhood to end that argument.

“I used to be treated like I was a hero.”

Adult Celeste insults and humiliates the sister whom she shoved into the background, even as her own daughter reminds her “You have everything she ever wanted.” As a mother, she gripes about what “giving the gift of life” cost her  — sarcastically, to her daughter. Mom’s got to stay skinny and sexy, got to abandon the past because in our culture, “The past is UGLY.”

And she’s got to stay in the saddle, performing and touring, with many mouths to feed — people depending on her — and a music business model that’s in shambles isn’t making it any easier.

Actor turned writer-director Brady Corbet takes us down this familiar road with pace and pathos, if few genuine surprises. He’s no more discovered something new in the “Star is Born/Star Endures” saga than Bradley Cooper, but he stages bracing concert scenes (Sia wrote the songs, Portman sings them in a Sia-style) in the Madonna/Gaga/Britney in Vegas manner — lots of dancers, vividly realized backstage rituals before the show.

But Portman so energizes the film you wish she’d shown up earlier than the midway mark. Covering ground this familiar cannot help but be a little tedious, and it might made the chilly, remote “Vox Lux” a film we could embrace if her empathetic star power and charisma were a bigger part of it.

MPAA Rating: R for language, some strong violence, and drug content

Cast: Natalie Portman, Jude Law, Raffey Cassidy, Willem Dafoe, Stacy Martin, Jennifer Ehle, Christopher Abbott

Credits: Written and directed by Brady Corbet, songs by Sia. A Neon release.

Running Time: 1:53