In Italy in 1939, a European man calling himself Mr. Imperium uses a ruse to meet an attractive American woman, Frederica Brown. He eventually is revealed to be Prince Alexis, an heir to the throne and a widower with a six-year-old son. He nicknames her "Fredda", so she calls him "Al". When his father becomes gravely ill, he must rush to be with him, but asks prime minister Bernand to deliver to Fredda a note of explanation. Bernand instead tells her the prince has left permanently, that this is his usual method of seducing and abandoning women. Twelve years go by. One day in Paris, a cinema's marquee makes it clear that "Fredda Barlo" is now a movie star. Fredda's former love travels to California, where film producerPaul Hunter is now in love with her and proposing marriage. Fredda decides to drive to Palm Springs to think about his proposal, as well as to decide which actor should co-star in her next film, about a girl who falls in love with a king. "Mr. Imperium" takes a room next to hers, and soon they meet and embrace. He explains the crisis that took place at home during the war and prevented him from looking for her. Now he wants a new life, and Fredda believes he could even portray a king in her film. Bernand turns up, however, to say that his son is preparing to ascend to the throne. Mr. Imperium realizes he is needed there, so he must say goodbye to the woman he loves once more.
According to MGM, the film earned $460,000 in the US and Canada and $295,000 elsewhere, resulting in a loss of $1,399,000. Mr. Imperium was an entertaining film with a troubled release; it was the first of two musicals MGM attempted with South Pacific stage-star and former Metropolitan Opera singer Ezio Pinza. When previews with test audiences proved disastrous, the second film, Strictly Dishonorable, was put into general release first, but with the same unfavorable results. One of the reasons cited for the failure of Mr.Imperium was its odd title, but the real problem with the film was Pinza as leading man. On stage in South Pacific, Pinza successfully appeared as a dashing, mature leading man; On screen, he came across as less of a matinee idol, and more of a “dirty old man,” to quote historian Donald L. Miller. Mr. Imperium played theatres mostly as a "B movie" second-feature, despite lavish MGM production, Technicolor, Lana Turner, and two pleasant Harold Arlen/Dorothy Fields songs, “Let Me Look At You” and “My Love and My Mule". MGM cancelled Pinza's contract after the box office failure of Mr. Imperium.
