In The Princess Diaries 3 (2025), Mia Thermopolis returns to Genovia after years abroad working as a global ambassador. Now in her early 30s, sheβs preparing to officially take the throne as Queen. But with the country facing political unrest and pressure from the royal council, Mia is urged to settle down and marryβsparking public speculation and personal doubt. Despite her success and growth, the weight of royal tradition still hangs heavily on her shoulders.
While navigating her new duties, Mia discovers a hidden set of letters from her late grandmother, Queen Clarisse, revealing a possible unknown heir to the Genovian throne. Determined to protect the kingdomβs future, Mia sets off on a discreet search, joined by her best friend Lilly and loyal advisor Joseph. Their journey takes them across Europe and back through Genoviaβs history, uncovering secrets that could reshape the royal family forever.
Back at the palace, Mia finds herself unexpectedly reunited with Nicholas Devereaux, the dashing nobleman from her past. Their rekindled connection stirs old feelings, but also new questions about love, power, and what Mia truly wants from her lifeβnot just as a queen, but as a woman. Meanwhile, a young Genovian journalist begins digging into the royal family’s affairs, stirring public tension and forcing Mia into the spotlight once again.
As pressure builds, Mia challenges the outdated royal customs and proposes reforms that would allow a queen to rule without being married. Her bold move divides the kingdom but earns admiration from younger generations. She hosts a historic summit in Genovia, inviting modern thinkers and allies, standing firmly for her values. Through emotional speeches and brave choices, Mia begins to transform the monarchy into something more inclusive and forward-thinking.
By the filmβs end, Mia ascends the throne not through tradition, but on her own terms. With Nicholas by her sideβnot as king, but as her partnerβshe becomes a symbol of modern royalty: compassionate, courageous, and independent. The Princess Diaries 3 concludes with a moving coronation, the birth of a more progressive Genovia, and a tribute to the lasting influence of Queen Clarisse, whose spirit lives on in Miaβs leadership.