“Wicked” doesn’t need a movie adaptation to be relevant — it’s already a cultural phenomenon, even before the behemoth two-part film adaptation hits theaters. The beloved 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 1 by the witch at the center of “Wicked,” Elphaba, in the show’s signature song, “Defying Gravity.” The battle cry that emerges from Elphaba (played here by Cynthia Erivo) is 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, which is 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, where the pair first encountered each other. 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 an.