From left: Sherri L. Edelen, Emma Hunton, Jason SweetTooth Williams and Heidi Blickenstaff star in the new stage musical “Freaky Friday.” (Margot I. Schulman)

Heidi Blickenstaff can tell you about her role in Signature Theatre’s new musical — it just takes a few sentences.

“I’m Heidi the actress playing Katherine the character in Ellie’s body, who is Emma [Hunton], the actress,” says Blickenstaff, whose Broadway credits include “The Little Mermaid” and “Something Rotten!” “But also, my character is trying to fake everybody out. So as Ellie, I’m trying to make everybody think I’m Katherine. It’ll make your head hurt if you think about it too long.”

In “Freaky Friday,” a world-premiere musical developed by Disney Theatrical Productions, Blickenstaff plays — at different times — both the mother and the daughter who switch bodies through a poorly timed bit of magic. The show, which opened Tuesday, is preceded by Mary Rodgers’ 1972 novel, a 1976 movie starring Jodie Foster and a 2003 remake starring Lindsay Lohan. This version, written by Bridget Carpenter (TV’s “Friday Night Lights,” “Parenthood”) with music by composer Tom Kitt and lyricist Brian Yorkey (“Next to Normal”), takes different elements from each of these. One thing Carpenter made sure to keep from Rodgers’ novel is its opening line: “So you’re never going to believe me.”

It’s spoken by Ellie (Hunton), an angry, bored 16-year-old who’s still recovering from the death of her father four years earlier. Her mother, a hyper-organized small-business owner, is set to marry a new man and is struggling to keep her family together. On the day of Katherine’s rehearsal dinner and an all-night scavenger hunt at Ellie’s school, bickering mother and daughter mysteriously swap bodies and have to live out the day in each other’s shoes. Sounds like after-school-special material, but Carpenter says they’re telling a much bigger story here than just a wacky adolescent adventure.

“It’s the story of a mother and daughter and their deep connection and disconnection. It is about growing up and wanting to be understood and listened to,” Carpenter says. “It is so human for every single person to go, ‘What would I do if I were in your shoes?’ Weirdly, I take this story seriously.”

Carpenter is a big fan of the source material — like, a really big fan. At 11 years old, she was accidentally locked in a bookstore after closing time because she got swept up reading Rodgers’ novel. As a reader, she fell in love with the acerbic young protagonist and the allure of 1970s New York City. As a writer, she’s trying to capture the intangible way teenagers behave and interact in 2016. So before you ask, yes, these kids — and adults, for that matter — are glued to their iPhones. She’s been sparing with modern-day touches, though, which is why you won’t find any jokes about “Game of Thrones” in her play.

“I try never to have any references that are right now because that means in six months the show will be dated,” Carpenter says. “I look at how I am as a mother, how my friends are as parents and what our kids are like. And I try to reflect these kids now; there’s something that’s inherently different.”

Emma Hunton in Freaky Friday Emma Hunton plays Ellie, who has a little bit of her mom in her. OK, a lot. (Margot I. Schulman)

She acknowledges the challenge she faced trying to ground a musical comedy that has magic in it. So her script embraces the little moments that make up a relationship.

“We’re saying that something impossible happened, but we’re going to take it seriously,” she says. “Magic is broad, but I hope we have the reality and heart and precision of ‘Friday Night Lights.’ ”

Those finely drawn portraits make Blickenstaff’s task of nailing the emotional cues “a little paint-by-numbers,” she says, even if the rest of her job is a lot harder. The actress, 44, was cast as mom Katherine, but she spends about three-quarters of the musical playing a 16-year-old. “My knees are definitely aware that I’m trying to get into the body of a teenager with all its quick stops and starts and flailing,” she says.

In fact, Blickenstaff and Hunton have gotten so good at playing each other’s characters that having to play them in their appropriate bodies has become the real challenge.

“Our director [Christopher Ashley] has said, ‘Watch Emma and how she does Katherine in this moment,’ ” Blickenstaff says. “I steal things from her for when I’m playing the adult, which I should know everything about.”

There are several moments in the show that hit home for Carpenter and Blickenstaff, both as parents and daughters. Some of that came out in the rehearsal room: the way that Katherine reaches to brush Ellie’s hair out of her face, for example. “It’s not because she thinks Ellie’s a slob it’s mostly because she wants to be close to her,” Blickenstaff says. “When the character is reversed, I’m constantly flinching when Emma comes to touch me. I have felt both sides of that.”

Blickenstaff, who hasn’t read the novel or seen either “Freaky Friday” film, is aware that people may walk in with visions of the goofy Lindsay Lohan movie dancing in their heads. But she and Carpenter are quite sure the show’s substance will surprise audiences.

“We’re definitely gonna have, like, Brownie troops coming and they’re going to have a great time,” Blickenstaff says, “but the show’s also gonna crawl into people’s guts and wring them out because it’s so deep.”

But what about the music?

Writer Bridget Carpenter worked closely with composer Tom Kitt and lyricist Brian Yorkey to tell “Freaky Friday’s” story, and the show’s pop-rock music does a lot of the emotional heavy lifting throughout. Take the early song “Parents Lie.” Heidi Blickenstaff, as daughter-in-mom’s-body, sings it to her little brother, Fletcher, who assumes it’s his mother singing. “The song is all about letting my ‘son’ know all the things that parents lie about,” Blickenstaff says. “Including [that] everybody hates broccoli, everybody sleeps through church and nobody flosses. But then it gets deeper about the bigger things parents lie about. … She ends up shattering his childhood.”

An earlier version of this story misstated when characters switch bodies. It has been corrected.

Signature Theatre, 4200 Campbell Ave., Arlington; through Nov. 20, $40-$108.

More arts in the D.C. area: 

The real mystery of ‘Shear Madness’: Who goes to see it — and why?

5 spots to celebrate African-American history and culture in D.C.

Eat, drink, laugh and dance at these fall festivals