British prince and president's son start a secret affair in Red, White & Royal Blue trailer

What would happen if the Prince of England and the son of the President of the United States embarked on a secret romance?

That's the story at the center of Red, White & Royal Blue, based on the novel by Casey McQuiston. Now a feature film starring Nicholas Galitzine as Prince Henry and Taylor Zakhar Perez as POTUS' son Alex Claremont-Diaz, as seen in EW and PEOPLE's exclusive trailer debut (below) for the highly anticipated adaptation.

Matthew Lopez (The Inheritance) makes his directorial debut on the Prime Video project, a role he was determined to nab after reading the novel.

"I first read the book in early 2020 and I decided I wanted to make the movie by page 100," he tells EW. "I fell madly in love with the characters and I wanted to bring them to life on the screen. I also was excited at the prospect of filming scenes set in the world of the presidency and the British Royal Family. I shamelessly harassed [producers] Greg Berlanti and Sarah Schecter into backing me with the studio to direct it. The idea that someone else might make this movie filled me with unbearable jealousy."

Lopez won the 2020 Tony Award for Best Play for The Inheritance, a gay epic inspired by Howards End. He received praise for its examination of the gay community in New York and inter-generational conflict and legacy. But now Lopez gets to turn his eye to a happier gay love story. "[I found] in the book something I had rarely seen on screen: a love story between two young men that is hopeful, funny, and deeply romantic," he adds.

The Red, White & Royal Blue trailer showcases the central love story between Henry and Alex, as they first clash and cause an international incident involving a cake at a royal wedding. Their attempts to put up a good PR front as friends — as ordered by their parents — lead to an unexpected romance and a connection that will test their public roles and the private leanings of their hearts.

Royal lovers will clock some parallels between Henry's love story and that of another younger son, Prince Harry, as they're forced to choose between duty and love. That was a clear reference point for Galitzine, maybe too much so. "There's obvious comparisons with Prince Harry and this young royal who doesn't really fit into the mold that has been laid out before him," the Purple Hearts actor tells EW. "Inevitably, a lot of people drew comparisons with Prince Harry. I tried to stay away from that because it's entirely its own thing. Henry is complicated in a different way and dealing with different issues. [They share] the concept of someone who was born into the public eye, but the responsibilities that he carries for his family and the pressures that come with that are entirely unique."

Still, Ellie Bamber, who plays Henry's reformed party-girl sister, Princess Bea, says that being British and growing up around the trappings of monarchy was an invaluable resource. "Just having seen the royal family on the TV here and there meant I could tap into certain things, the physicality — how they carry themselves and the way they talk," she says. "Seeing how much press attention they've consistently had really helped me get into Bea's head and to understand her past a bit more."

This isn't Galitzine's first time playing a prince. He also portrayed a charming royal, Prince Robert, in 2021's Cinderella starring Camila Cabello. But he notes that Henry was a lot more down-to-earth and grounded than Robert. "Robert is much more happy-go-lucky. He's much more playful," he explains. "Whereas with Prince Henry, there are definitely comedic aspects and it's such a fun, light movie in a lot of ways. But Henry is definitely more emotional and internalized with how he expresses himself. Much more in line with how people see royals."

Galitzine relished the challenge of portraying Henry's vulnerabilities and his own struggles in sharing them with Alex. "As men, we find it hard to express ourselves and express our feelings," he says. "But that was a fun thing to explore from an acting perspective. [I was] trying to understand that this person is entirely trapped by his upbringing and his family. And the wedge being placed between his family and the person he loves is a very difficult thing to contend with. That was probably the most challenging, trying to make that authentic and real."

What wasn't hard? Finding chemistry with Perez. "We have the same sense of humor," says Galitzine. "We're both idiots in some way. We speak the same language as people. It was a different chemistry. Finding the levity and the light in each other, finding a sense of play in the scenes. Because you want them to have that banter that back and forth, that zippy dialogue."

Lopez says the actors' easy chemistry and charm are part of why he chose them for the roles. "Nick brings a tremendous amount of vulnerability and dignity to Henry," he says. "Taylor turned himself into a human cannonball in order to bring Alex to life."

But the thing that weighed most on all of them was not royal protocol, chemistry, or even comedic timing. It was honoring McQuiston's novel, which hit the New York Times bestseller list and even earned a release in a special collector's edition last year.

"[The biggest challenge was] quite simply how to delivery Casey's story in a way that honored the novel but that didn't result in a three-hour film," says Lopez. "There are a lot of wonderful scenes and characters in the book that didn't make it into the film because they didn't fit. I don't regret any of those decisions but, as a fan of the book, they weren't easy to make."

Fans can find out what those tough decisions were when the film hits theaters on Aug. 11. Watch the exclusive trailer above for more.

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