Taking an unfamiliar route to a well-traveled destination, the music-fueled comedy-drama “The High Note” is a witty, warm-hearted story about the recording industry seen from the top and the bottom.

On top is Grace Davis (played by “Black-ish” star Tracee Ellis Ross), a superstar singer whose career has spanned more than 30 years, and is facing the prospect of becoming a “legacy” act. Her longtime manager, Jack Robertson (played by Ice Cube), is nudging her toward signing a contract with Caesars Palace for a Las Vegas residency — a sure sign that her hit-making days are over.

Far below Grace is her personal assistant, Maggie Sherwoode (Dakota Johnson), who has toiled for this demanding diva for three years. Maggie is tasked with picking up the star’s dry cleaning, ordering her favorite smoothie, keeping her schedule and making excuses to extract Grace from conversations she wants to avoid.

Maggie grew up with music — her dad (Bill Pullman) was a rock journalist and her mom, who died when Maggie was little, was a singer — and knows the classics, including Grace’s repertoire, better than anyone. She also harbors dreams of being a producer, and on her infrequent off hours tries her hand at remixing Grace’s tracks.

When Maggie argues that Grace should release an album of new songs, Grace is interested but also scared — because she knows well that only five women over 40 have ever charted a No. 1 song, and only one of them was black. (Trivia answer: Tina Turner.) Meanwhile, Jack pointedly reminds Grace of her place in the industry food chain.

When a suave, sweet guy starts talking music with her at the grocery store, Maggie is resistant to the flirting. But when the guy, David (Kelvin Harrison Jr.), turns out to be a talented soul singer, Maggie sees that he could be a star with the right producer. Maggie, without telling him about her day job, convinces David to let her produce his songs.

First-time screenwriter Flora Greeson creates characters whose passions drive them, sometimes into conflict, but always toward the goal of making music. And Greeson’s ear for good music comes through in passages where Maggie, David and Grace talk about their influences. Gleeson does commit some rookie mistakes in the story mechanics, especially a late plot twist that nearly sinks the whole enterprise.

Director Nisha Ganatra displays the same skills here that she deployed in her 2019 Sundance breakout “Late Night.” Those include sparking good chemistry between her sharp female leads, drawing comic relief out of supporting players Zoe Chao (as Maggie’s supportive roommate) and June Diane Raphael (as Grace’s clingy household manager), and highlighting the grit and hard work under the glossy surface of a performer’s life.

Johnson, the “50 Shades of Grey” franchise firmly in her rearview, revels playing the plucky lead of this underdog story — and, in her scenes with Harrison, she shows she’s got the romantic-comedy moves, too. Ice Cube, rap music’s original angry young man, plays a “suit” with gusto, and gives Jack just the right amount of street hustler.

The most fascinating turn in “The High Note” belongs to Tracee Ellis Ross, because of how she defies expectations. One might look for echoes in Grace of Ross’ famous mother, Diana Ross. Sure, Miss Diana’s larger-than-life persona informs aspects of her daughter’s riveting performance, but that doesn’t account for the light touch, the self-deprecating humor, that the younger Ross brings to the table. Oh, and she can sing, a revelation that ends the movie, yes, on a high note.

★★★1/2
‘The High Note’
A veteran pop star and her overworked assistant hit a crossroads that could change both of their futures in this warm, witty comedy-drama.
Where • Video-on-demand platforms — including Prime Video, Apple TV, Xfinity, Vudu, Google Play and Fandango Now — for $19.99 rental.
When • Available starting Friday, May 29.
Rated • PG-13 for some strong language, and suggestive references.
Running time • 113 minutes.