“Saving Zoë” deserves praise for the business savvy of its stars and producers, Vanessa Marano and her younger sister Laura Marano.

They had the foresight to get the rights to an Alyson Noel novel about a younger sibling trying to figure out what happened to her dead sister. Even if they were years away from graduating from kiddie TV — “Austin & Ally” and Netflix’s “The Perfect Date” for Laura, “Boys are Stupid: Girls are Mean,” “Switched at Birth” and “The Dead Girls Detective Agency” for Vanessa — this R-rated project had the potential to help them move on from kids’ roles into more adult fare.

And if it doesn’t quite achieve “moving,” even if they’re not quite up to carrying it, TV acting habits being hard to break and all, even if they’re upstaged by the actress with the showiest role — Giorgia Whigham plays a broken, guilt-ridden party girl and friend of the deceased — “Saving Zoë” has a hint of the risk they figured was worth taking with it.

Younger sister Echo (Laura Marano) is the one left behind, no big sister to guide her through that first day at Lincoln/Carter High in suburban Ohio (actually, Augusta, Georgia).

But actually, big sister is, assuring her “Everything’s going to be OK” as they share a makeup mirror.

Mom (Whitney Goin) is a wreck on her “zombie meds.” Dad’s practically living at the office.

And everybody on the bus hits Echo with that pinched embarrassed “You poor thing” look, as if she’s just punched them.

It doesn’t matter that she sees big sis is on the bus a few rows in front of her, or striding confidently down the halls with her. Nobody else sees Zoë, because she’s dead.

“I just want to say how sorry I am, about Zoe.”

As Echo tells her BFF (Annie Jacob), “There’s awkward, and then there’s this.”

Hearing that “Eventually, everybody’s going to move on,” is cold comfort.

Marc (Chris Tavarez), the dead girl’s boyfriend, was cleared of her murder. Even though  Zoë’s body was found in his car, even though he was the last one to see her alive.

The family shrink (Ken Jeong) isn’t helping Mom or Dad (Jason Davis), and his questions about how Echo felt “stuck in Zoë’s shadow” don’t do Echo any good at all.

The one classmate who treats her openly and emotionally is the dead sister’s friend, Carly (Whigham), who calls her “Baby Sister” when she’s not so plastered she confuses Echo for her sister. And when she’s confused, all she does is apologize to her.

Echo gets her hands on Zoë’s diary and cozies up to Carly, because whatever the trial of her confessed killer told her about her sister’s death, she’s starting to figure out she didn’t know her sister, and that Carly knows more than she told the cops.

Veteran TV camera operator turned director Jeffrey G. Hunt and the screenwriters tell this story in that conventional “dead girl tale” way. Vanessa Marano narrates Zoë’s last months of life, and acts out the romance, pitfalls, hopes and dreams of a pretty girl who expected her looks to take her far,  “modeling, or acting, anything to get me out of this dump.”

“Someday, everybody’s going to know my name!”

“Saving Zoë” lumbers through the narrative conventions of such stories, hitting the occasional lurid note — Echo’s first trip with “Molly,” Zoë’s sex life, and the dark sexual pitfalls she stumbled into in pursuit of “everybody’s going to know my name!”

But the picture has a stolid competence about it that it never rises above, with Netflix-ready teen titillation written all over it. Netflix is the Lifetime Network of teen sex comedies and dramas.

The sibling leads are professionals, but don’t have the chops to make us ache for Zoë’s fate or fear for Echo’s.

Only Whigham, bleary-eyed and lurching from high-to-grief-stricken, makes much of an impression. She’s good enough to make you wish she had a younger sister (she’s the daughter of top drawer character actor Shea Whigham) to pair up with for this.

MPAA Rating: R for disturbing violence/rape, nudity, language, drug use, drinking, and brief sexuality – all involving teens

Cast: Laura Marano, Giorgia Whigham, Vanessa Marano, Ken Jeong

Credits: Directed by Jeffrey G. Hunt, script by Brian J. Adams and LeeAnne H. Adams, based on the Alyson Noel novel.  A Blue Fox Entertainment release.

Running time: 1:35