The interwar European economic crisis is also felt in the small kingdom of Silvaria. The state coffers are miserably empty and only a miracle can avoid bankruptcy. Here one day a young American billionaire, Mary Lloyd, who travels the world in search of new excitement, arrives and buys the royal castle of Silvaria, securing a hefty sum for the agonising state budget. Everyone rejoices except the proud prince Sandor Boris with whom Miss Mary immediately falls in love. With the swiftness that characterises Americans, the Castle of Silvaria is completely transformed; the one who has the time of her life is Princess Rose Marie, who begins an affectionate relationship with Miss Mary's secretary, Mister Bondy. To facilitate this union, King Pancras gives Bondy the title of Count. The skirmishes between Miss Mary and Prince Sandor continue until the prince, in a finale full of twists and turns, confesses his love to Miss Mary.