In the late 1940s, Seretse Khama, the heir to the throne of Botswana, meets and falls in love with Ruth Williams, a white London office worker. Despite their different backgrounds and the racial prejudices of the time, the couple marries, causing a scandal in both their home countries. Their union faces strong opposition from their families and the British government, which is concerned about its diplomatic relationship with South Africa, where apartheid policies are strictly enforced. The couple's love and commitment to each other must withstand intense political pressure and social backlash.

As Seretse attempts to return to Botswana with Ruth, they encounter resistance from the local tribe elders and British authorities who question his suitability as leader due to his interracial marriage. Facing monumental obstacles, Seretse and Ruth fight to gain acceptance from both Seretse's people and the wider world. This steadfast commitment to each other and justice gradually shines through in their personal lives and their political endeavors. Their struggle becomes a symbol against racial discrimination and a pivotal moment in the history of Botswana.