It's the beginning of another school day, and the students, led by brainy senior Natalie Watson, brace themselves for all the coming frustrations, freak-outs, and fears, singing "Ready or Not."
The action moves to Playa Sola High School where we meet the popular slacker/surfer Kyle Fairbanks. The upcoming prom "Magical Night" is on everybody's minds, and Kyle's gorgeous yet snobby girlfriend and her cadre of fashionistas lay down the rules about just how they expect to be asked to prom in "Do It Right."
In English class, Natalie is asked to present her oral book report. Of course, overachiever Natalie can't summarize just one book and shares three biographies of feminist pioneers singing "Makin' It" (in a man's world). Afterwards, Ms. O'Brien almost nails Kyle for not being prepared, when the bell rings. Brad, Kyle's friend, asks him if he's ready (and reminds him his dad said, "No prom," if he's failing. Despite Brad's urgent warning, Kyle tells him to relax as he looks across the classroom at Natalie. "Would you relax, man," he says, "I'm on it."
Later in the high school common area, computer geek Freddy asks Shelly to the prom. As much as she'd like to go with him, she turns him down -- going to prom with Freddy would never be cool enough for her to hang with Ashley and her posse. In a pretty sleazy attempt to get Natalie to do his book report, Kyle comes on to Natalie, singing "Get a Life," but Natalie sees right through him. After Kyle leaves, Natalie's best friend Claire ask her about the encounter, but Natalie dismisses the whole thing, telling Claire, "you know what they call girls who's greatest achievement in high school is being popular -- the real housewives of Orange County." Natalie's phone rings, and she finds out from her mom that she's a finalist in the Edna Quinn Bellows Public Speaking, College Scholarship Contest.
The next day, on a school field trip to a historic mission -- The Mission of Weeping Maiden -- Garrett, an enthusiastic storyteller with an interest in all things otherworldly, asks about the mission's name. Chloe, their guide, tells him about a Native American maiden, who threw herself in the mission's well they now stand before, when her love for a young Spanish nobleman was forbidden, "after which, half the town dies of dysentery," she tells them. Garrett then whips the kids into a frenzy, singing "Supernatural." After the kids disperse, Kyle and Natalie find themselves at the well together. In an angry confrontation, they begin throwing coins in the well, wishing curses at each other. "I wish that someday Kyle Fairbanks finds out what a jerk he is," Natalie says. "And I wish that Natalie Watson realizes how boring life is when all you do is homework!" Kyle says back at her. There is a clap of thunder, the lights dim, and in the darkness, accompanied by mystical music, Kyle and Natalie's brains mysteriously switch places into each other's bodies.
The next morning, Kyle (Natalie) and Natalie (Kyle) [from this point in the synopsis, the name of the mind of the character is in parentheses] realize their brains are in one another's bodies and sing, "Back Where I Belong." They both rush to school, Kyle (Natalie) now dressed in a shirt and tie (because that's how Natalie dressed him) and Natalie (Kyle) in a slinky cocktail dress (because Kyle does the same), and they realize they're stuck this way until they can get back to the mission, which doesn't open until ten. Natalie (Kyle) asks Kyle (Natalie) for a favor. "Can you hook my bra for me?" she asks. "What?!" Kyle (Natalie) asks. "I've been tryin' to get this stupid thing hooked for the last half hour." Of course, the minute he does, Brittany, one of Ashley's posse walks past and sees the whole thing.
In "Texting Song," word spreads like wildfire as everyone eventually finds out "there's something goin' on between those two." As Brad and Claire try to sort out their best friends' bizarre behavior, they become friends. When they overhear Kyle (Natalie) and Natalie (Kyle) planning a trip back to the mission, they follow them. At the well, Mr. Molina, the caretaker, scolds Kyle (Natalie) and Natalie (Kyle) for treating the mission like a "chamber of horrors." Natalie (Kyle) remembers he's got a date with Ashley to ask her to the prom, and Kyle (Natalie) agrees to help him out with it. After they leave, Brad and Claire try to make sense of what they've seen. As they ponder the possibilities of a wishing spell, they begin to share their own desires and secrets, singing "Wishes." Afterwards, Brad asks Claire to the prom. She accepts.
That night, Kyle (Natalie) takes Ashley on the perfect date -- a romantic dinner on the beach, complete with appetizers, poetry and napkin holders. Kyle (Natalie) then sees an eclipse is beginning and realizes she's got to get back to the well.
At the well, Kyle (Natalie) and Natalie (Kyle) attempt to reverse the spell by writing their wishes on papers and dropping them in. When the attempt fails, they check to see if the eclipse has reached totality. Kyle (Natalie) lifts Natalie (Kyle) up on the well to look over the trees, and as he steadies her, Ashley walks in, convinced Kyle's two-timing her. Natalie (Kyle) begs Kyle (Natalie) to tell Ashley that he could never be interested in someone as "ordinary" as Natalie, and follows her off. Alone, Kyle (Natalie) realizes the price she's paid to stay true to herself and her goals, singing "Being Me." Natalie (Kyle) returns and realizes how much what he's said has hurt her. He tries to apologize, but both furious and hurt, Kyle (Natalie) leaves. The act ends with Natalie (Kyle) vowing to get things right as she sings a reprise of "Back Where I Belong."
The second act opens with Garrett, still trying to get to the bottom of all this weirdness, leading the rest of the cast in singing "What Comes Next." Then Natalie (Kyle) asks Kyle (Natalie) how he's going to patch things up with Ashley. Kyle (Natalie) tells Natalie (Kyle) not to worry, he's got it all worked out. As Natalie (Kyle) listens in, Kyle (Natalie) smooths things over, giving Ashley an Amazonian Orchid. Then, after Kyle (Natalie) leaves, it becomes clear that Ashley still feels her position as the hottest girl in the school is threatened singing, "Suspicious." Ashley sees Natalie (Kyle) making her exit and tells her that if she ever thought Kyle was really interested in Natalie, she'd drop him "so fast he'd have to be treated for whiplash." The conversation begins to give Kyle a clearer picture of Ashley's coldness. After they leave, Brad and Claire discover Kyle's to-do list. When they read Kyle's (Natalie's) first task is to "decontaminate Kyle's sock drawer," they begin to realize their friends just may have switched brains.
When Kyle (Natalie) and Natalie (Kyle) get together to rehearse Natalie's speech for the scholarship competition, things suddenly start to change. Instead of irritating each other, a mutual (and slightly terrifying) attraction begins to develop in "Being With You."
Shelly unexpectedly shows up at the computer lab, looking for Freddy. She tells him she was stupid not to say yes when he asked. They make it a date, and let each other know how they really feel singing "Download My Love."
At the Edna Quinn Bellows College Scholarship Speech Competition, Natalie (Kyle) has a flash of inspiration in the middle of Natalie's speech, and compares Susan B. Anthony and Elizabeth Cady Stanton to world-record-holding surfer Mike Parsons. After the speech, Kyle (Natalie) is furious when Skeeter Quinn Bellows, a surfing fanatic and Edna's nephew, gives Natalie (Kyle) the award. However, Kyle (Natalie) can't accept the award, since it wasn't her speech that won the prize. Natalie (Kyle) begins to realize how he never really appreciated Natalie and romance blossoms as they sing "Gonna Stay With Me." Ashley suddenly arrives, furious at the obvious attraction between them. At Natalie's (Kyle's) direction, Kyle (Natalie) breaks up with Ashley. Then Natalie (Kyle) asks Kyle (Natalie) to the prom. When she balks at the idea, Natalie (Kyle) tells her, "Okay, look at it this way. If I'm going to go to the prom with some guy, it's gonna be me."
In "Magical Night," the cast arrives at the dance, where Ashley plots her revenge, planning to put a mysterious something in Kyle's drink. Word gets out what she's planning, and through the course of the dance, Ashley's spiked drink circulates among the cast. As they sing, "...never gonna be another night as magical as this," no one's quite sure just who's drinking what.
Then Garrett happens to tell Brad and Claire what he's learned about the myth of the well -- the poem in the plaque there can be translated to read, "...then comes the changing minds." They tell Natalie (Kyle) and Kyle (Natalie) and everyone rushes to the mission's well where they once again try to get their own minds back. As they arrive there, Mr. Molina explains to them that an expression of genuine caring might convince the spirits to undo their magic. Kyle (Natalie) and Natalie (Kyle) kiss, and magically, the spell is broken. Ashley arrives, her hair now turned bright red, having literally taken her own medicine, and all ends happily for the rest of the cast as they sing, "Ready, Next, Go."