Plot

When Duchess Margaret unexpectedly inherits the throne to Montenaro and hits a rough patch with Kevin, it's up to her double Stacy to save the day before a new lookalike, party girl Fiona foils their plans.

Stacy is now the Princess of Belgravia, while Margaret is preparing to ascend to the throne of Montenaro following the death of the king and the decision of his son Howard to abdicate. Nervous about taking on the responsibilities of ruling a nation, Margaret has ended her relationship with Kevin, who is now running his own bakery with Olivia in Chicago.

Stacy makes a surprise visit to Chicago on her way to the coronation and finds Kevin miserable since the breakup. When Olivia reveals she never mailed in the RSVP to the coronation, Stacy persuades him to reconsider and travel with her and Prince Edward, even though the couple has their own relationship problems as Stacy has increasingly neglected Edward while she focuses on her duties as Princess.

Upon arriving, Kevin reunites with Margaret and helps her, Prince Edward, Stacy, and Olivia decorate her palace for Christmas. Margaret also feels depressed about how things ended with her and Kevin. At an evening event, they dance, only to be interrupted by Lady Fiona Pembroke, Margaret's cousin.

Unbeknownst to anyone, Fiona has spent nearly all of her family's small fortune and has resorted to using her servants Reggie and Mindy to rob the guests at the party. Back at the decrepit Pembroke estate, Fiona suddenly has an idea: to assume Margaret's identity, get crowned as queen, and loot the royal treasury, setting her up for life. Reggie and Mindy are enthusiastic and help Fiona dye her hair and copy Margaret's makeup while studying the queen's upcoming schedule.

Back at the palace, Margaret admits that she's been too busy with royal affairs to spend time with Kevin. Complicating matters further is Count Antonio Rossi, her chief of staff, who woos her and plants seeds of doubt in Kevin's mind that he could ever be a good match for a future queen.

Stacy decides the only way to fix things is for her and Margaret to switch identities again so she and Kevin can have the afternoon to themselves while Stacy takes care of Margaret's schedule. The switch takes place, with Olivia staying behind to distract Edward while Margaret and Kevin go to a local Christmas park. There, Kevin expresses his doubts about being Margaret's equal and she convinces him that such concerns are irrelevant as long as they love each other.

Reggie and Mindy abduct Stacy, thinking she's Margaret, locking her up in Pembroke Manor. Fiona steps in just as Margaret returns. Realizing that the woman she's speaking to isn't Stacy, Margaret explains the truth to Prince Edward. They then rescue Stacy from Reggie and Mindy, who are arrested and reveal Fiona's plan.

Meanwhile, Antonio deduces the truth on his own as Fiona forgot to cover up a tattoo on her finger. He tells her that he will move up the coronation and help her escape the country if she agrees to divide the treasury with him, as he also needs money.

Just as the coronation is about to take place, Margaret and Stacy arrive and expose Fiona and Antonio. The latter is arrested while the former admits her deception and reveals that Kevin is on his way to the airport with Olivia after she told him she didn't want to be with him anymore.

They stop Kevin just as he is about to board a plane, and he and Margaret get married on the spot officiated by a nearby priest. Stacy and Edward reaffirm their love for each other as she promises to make more time for them, and he promises not to smother her with attention. Margaret is crowned Queen of Montenaro with Stacy, Edward, Olivia, and Fiona (escorted by police) cheering her on.