The biopic is based on a story that happened to Seretse Khama, a prince from Botswana. In the late 40-ies of the last century, a man fell in love with an Englishwoman, which greatly complicated his life. However, the aristocrat showed an enviable strength of will, achieving the desired. The film "The United Kingdom" will show how Seretse arrives in London. Here, in one of the jazz clubs, he meets a white Ruth Williams and immediately falls in love. The woman reciprocates and it may seem that the heroes have no obstacles in order to become happy. But as soon as the couple learns about the novel, their lives are filled with various tests. The first to face difficulties is Ruth, whose father is an ardent opponent of the connection of his daughter with a black prince. Despite this, she agrees to marry Seretse and with him leaves London, assuming the thought that he will never return home. When they arrive in Botswana, it will not become easier: the locals, the sisters of Seretse and his father, who will force the son to abandon the throne, try to destroy the heroes' love.