As variations on “We can’t see each other anymore” go, this film’s plot has novelty: After enjoying a wonderful first date in postwar London, the young woman makes it clear to the young man that she would like to see him again. He hesitates, clearly preparing to tell her the truth about something. The sad thing is, he explains, his grandfather was a royal personage and his parents died young, so he really must return to his native country and be—you know—the king. This is not the beginning of an Ernst Lubitsch comedy from the 1930s, but a slice of history based on the story of Seretse Khama (David Oyelowo, from Selma), the royal heir of Bechuanaland—now called Botswana—and Ruth Williams (Rosamund Pike), the Englishwoman he married.
In A United Kingdom, the marriage of a black African man and a white British woman is an important part of the plot, and for the first half-hour or so it appears this is what the film will be about.