The film—based on the stage musical, in turn based on Gregory Maguire's novel—follows green-skinned outsider Elphaba (Cynthia Erivo) and perfectly popular pink princess Glinda (Ariana Grande) during their college years, long before society forces them into the roles of the Wicked Witch of the West and Glinda the Good during the events of The Wizard of Oz. Grumpy British prime minister Sam Clarke (Idris Elba) and action-movie star turned US President Will Derringer (John Cena) can't stand each other—so teaming up to survive after Air Force One is shot down over the Belarusian wilderness is going to put a real strain on the Special Relationship.