Princess Rosalinda María Montoya Fioré Demi Lovato is poised to be crowned queen of the small nation of Costa Luna, a moment that should crown her with royal duty and ceremonial glory. Yet the tranquility of her coronation rehearsal shatters when General Magnus Kane [Johnny Ray Rodríguez], the dictator eyeing Costa Luna from across the border in Costa Estrella, storms the palace with a cadre of agents intent on seizing the throne. In the chaos, Major Joe Mason [Tom Verica], a seasoned agent of the secret Princess Protection Program (P.P.P.), whisks Rosalinda away to safety by helicopter, a daring escape that leaves her widowed mother, Queen Sofía [Dale Dickey], behind in danger.
With Rosalinda in hiding, the P.P.P. is tasked with a delicate mission: find a lawful way to topple Kane and restore the royal family. They relocate Rosalinda to Joe’s quiet home in Lake Monroe, Louisiana, where she encounters Joe’s daughter, Carter [Selena Gomez], a stubborn, tomboyish teen who spends her days at the family bait shop and dreams of the homecoming dance. Carter’s world feels unfinished—she longs for the correct moment to shine and to step into her own identity—while her classmate Ed [Nicholas Braun] quietly harbors a crush on her that adds to the tangled web of teenage longing. Rosalinda, meanwhile, adopts the alias “Rosie Gonzalez,” presenting herself as Carter’s cousin from Iowa, a cover designed to protect her while the Costa Luna crisis unfolds.
Despite a rocky start, Carter’s skepticism softens as Rosie opens up about her peril and her homeland. The two forge a bond that blends sisterly care with high-school camaraderie. Rosie teaches Carter how to navigate the social minefield of their peers, while Carter shows Rosie how to blend in as an ordinary American teen—learning to dodge the cruel gossip of the school’s mean girls, Chelsea Barnes [Jamie Chung] and Brooke Angels [Samantha Droke]. The two become an unlikely duo, drawing strength from each other as they juggle friendship, danger, and the weight of a larger political conspiracy.
The threat intensifies when Kane reveals plans to force a marriage between Rosie’s royal family and his own, using the marriage as a lever to consolidate power. Carter, ever resourceful, hatches a bold plan to draw Kane out of hiding by disguising herself as Rosie and playing bait at the upcoming homecoming dance. She enlists the help of Mr. Elegante [Ricardo Álvarez], the royal dressmaker and trusted ally to Rosie, who promises a dress that will fool even a vigilant dictator. In a twist of cunning, Rosie agrees to attend the dance, masking her royal identity while the two girls attend as Carter and Rosie.
The night of the dance becomes a turning point. A masked trio of friends—Rosie, Carter, and their allies—slips into the gym where the homecoming queen vote will decide the night’s fate. The plan hinges on deception: Kane’s men believe Carter, in Rosie’s persona, is Rosie herself, guiding her toward Kane’s helicopter. Yet the ruse starts to unravel when Rosie wins the homecoming crown, a triumph that could expose the ruse and jeopardize the mission. Rosie, however, makes a courageous choice: she reveals herself and asserts that this fight is not just hers alone, urging Carter to keep her own path and join the fight for their shared cause.
Backstage, P.P.P. agents—led by Joe—have been waiting inside the helicopter, ready to intervene at the crucial moment. The rescue unfolds with precision: Kane and his henchmen are captured and handed over to international authorities, and the two young heroines emerge from the peril wiser and more bonded than before. The victory is not merely a rescue but a fulfillment of the people’s hope for stability in Costa Luna, crowned by a public acknowledgment that courage and loyalty can triumph over tyranny. In the aftermath, Rosie is celebrated alongside Carter, with Joe, Ed, Sofía, and Mr. Elegante witnessing the turning of the tides. The scene closes on a hopeful note as Rosalinda ascends to her royal duties, and Carter discovers a future that blends her dreams with the responsibilities of friendship and resilience.
