Skylar Astin and Cast of Disney Plus' 'Secret Society of Second-Born Royals' on Magic of the Film (Exclusive)

Disney+ is exploring what it means to be second to the throne in its upcoming tween fantasy film Secret Society of Second-Born Royals. ET exclusively premieres the first look of a behind-the-scenes featurette, revealing new footage from the movie. (Watch the video above.)

Secret Society of Second-Born Royals follows Sam (Peyton Elizabeth Lee), a rebellious teenage royal who develops superpowers from a genetic trait attributed to second-borns of royal lineage. Second in line to the throne of Illyria, Sam questions what it means to be royal and instead wants to create her own legacy. Fed up with her daughter’s misbehavior, Queen Catherine (Elodie Yung) sends Sam to a summer boarding school where she and four other second-born royals discover they have superhuman abilities and are invited to join a secret society. With a new sense of purpose and help from Professor James Morrow (Skylar Astin), Sam and her fellow royal recruits learn to harness their newfound powers and work together as a team before they can save the world.

"I just love the originality and the concept. I liked that it celebrated the second-born because I'm a second-born, and I thought it was a fascinating concept that [Zoey's Extraordinary Playlist creator] Austin Winsberg, who created the story, told me about when I was first filming the pilot of Zoey's," Astin tells ET over the phone. "I was just so blown away, and when I found out there was an open role for me, I was excited that they asked me to do it."

The 32-year-old actor says his character, James, serves as a mentor to the young second-born hopefuls -- "a Professor Xavier of sorts," referencing the iconic X-Men figure -- and "introduces them to their new world and what they should expect from their newfound abilities." Of course, James won't be a stranger when it comes to wielding his own powers: "I partake in some of that action -- and comedy as well," teases Astin, who also narrates the film.

For the Zoey's Extraordinary Playlist star, being part of a fantastical world such as Secret Society of Second-Born Royals fulfilled a childhood dream. "I definitely always dreamed of both being a Disney prince and being a superhero, so to be able to cross them off the list in one film was pretty awesome," Astin said with a chuckle. "When I got fitted for the super-suit, it was very exciting, and the fact that I have a form-fitting super-suit -- I had action figures growing up... yeah, this was a dream and something I had a lot of fun doing."

As for the rest of the cast, the appeal of the movie rests on the real-world themes that will resonate with audiences, no matter what age they are. 

"After watching, I hope viewers realize that everyone is born with a superpower -- originality," This Is Us actor Niles Fitch, who plays fellow second-born royal recruit Tuma, says in an email to ET. 

"One of the main aspects of Secret Society of Second-Born Royals that really excited me was the level of relatability throughout the story. Even though it is centered in this sort of magical world where there are kings, queens, princesses and superpowers, it is grounded in that heightened reality, and still relates to the real world," Lee tells ET over email. "My character Sam struggles with the pressures that come with being royalty and having an entire country’s eyes on her to set the right example. Although most teenagers aren’t struggling with being the daughter of the Queen, the sentiment of fearing you won't live up to everyone’s expectations is a feeling everyone knows all too well. It is so important that we weave authentic and relatable stories into the shows and movies we create to not only entertain viewers, but also to make them feel less alone, and validate them in their feelings and experiences." ​

Other members of the cast include Olivia Deeble as Roxana, Faly Rakotohavana as Matteo, Isabella Blake-Thomas as January, Ashley Liao as Eleanor, Noah Lomax as Mike and Greg Bryk as the villainous Inmate 34.

Secret Society of Second-Born Royals drops Friday, Sept. 25 on Disney+.

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