“Wicked” doesn’t need a movie adaptation to be relevant — it’s already a cultural phenomenon. The Tony-winning Broadway musical is adapted from Gregory Maguire’s 1995 novel “Wicked: The Life and Times of the Wicked Witch of the West,” a revisionist history of Frank L. Baum’s 1900 fantasy novel “The Wonderful Wizard of Oz,” and that book’s iconic 1939 film adaptation “The Wizard of Oz.”

While Dorothy’s tornado- twirl into Technicolor is burned into our collective consciousness, so too is the massive note sung at the end of Act One, by the witch at the center of “Wicked,” Elphaba, in the show’s signature song, “Defying Gravity,” written by Stephen Schwartz (who wrote all the music and lyrics for the show). Director Jon M. Chu’s oversized movie adaptation takes every second of its two hours and 40 minutes to build up to that one note.

The battle cry that emerges from Elphaba (played by Cynthia Erivo) is a moment in which the anti-tyrannical ethos of the film snaps into sharp focus with such crystal clarity that it’s breathtaking. It’s just the preceding rising action that feels a bit underwhelming.

“Wicked” seeks to understand the Wicked Witch of the West, and the movie, written by Dana Fox and Winnie Holzman (who wrote the musical book), starts off when a denizen of Munchkinland dares to ask Glinda the Good Witch (Ariana Grande), in her big, pink bubble, “Is it true you were friends with her?” inspiring a flashback to their days at Shiz University.

Elphaba, rejected by her father since birth due to the color of her green skin, finds herself enrolled at Shiz when she follows her sister, Nessarose (Marissa Bode), to school and accidentally unleashes some untrained powers, catching the eye of Madame Morrible (Michelle Yeoh). She is forced to bunk up with pretty, popular, pink-obsessed Galinda (the first iteration of the Good Witch’s name), and though they are at first at odds, Galinda can’t resist a makeover, or the intriguing powers of her new pal.

It’s essentially a high school musical, with more magic, but not enough movie magic. The script has got to get Elphaba and Galinda to Oz to meet the Wizard (Jeff Goldblum), and hone Elphaba’s motivation for eventually defying the wizard (and gravity), which is wrapped up in a rushed subplot about talking animals being shunted out of society.

Grande is delightful as Galinda, showing off her comedic gifts and superb voice. Bowen Yang does heroic work with a few ad-libs and reactions as Galinda’s pal Pfannee, and Jonathan Bailey is terrific as the dashing prince Fiyero, but the setting doesn’t feel well rounded on the screen.

Chu has done dazzling movie musical work previously with “In the Heights,” but despite the elaborate costume and production design, “Wicked” is his least visually imaginative film. The camera is liberated (via CGI) in the song-and-dance numbers, but everything else is filmed in a basic, boring fashion, the background melting into a dim, unfocused blur behind the actors.

But “Wicked” will delight fans of the stage production as a faithful adaptation that is at once playful but reverent to the iconic “Defying Gravity,” and the story of understanding and togetherness despite social power structures that depend on fear and divisiveness.

But the weight of expectations is a heavy thing to bear, and they bog down this capable movie version on its way to liftoff. The film may struggle to take flight, but when it does, it is undeniably moving, with a message of freedom and defiance that resonates.

MPA rating: PG (for some scary action, thematic material and brief suggestive material)

Running time: 2:40

How to watch: In theaters