A United Kingdom is a thoughtful period film that asks its audience to meet it halfway. Its opening act nearly veers into a tawdry melodrama, with scenes that value social import over accuracy and nuance. But screenwriter Guy Hibbert is more ambitious than that, and the action shifts toward a thorny mix of politics, diplomacy, and colonialism. Like its two lead characters, played to perfection by underrated character actors, Hibbert and director Amma Asante rise to the challenge of the situation in which they find themselves. There are no histrionics here, so the film stays under the radar of awards season hype, and yet that should not detract those who crave romances with depth.

It is 1947 in London, and Seretse Khama (David Oyelowo) is wrapping up law school abroad. He meets Ruth Williams (Rosamund Pike) at a dance party, and the pair are inseparable. They wander the streets all night during their first date, and Seretse confesses something before they part: he is the prince of Bechuanaland (now Botswana), and after law school, he plans to return home and reclaim his birthright, becoming King. The news does not deter his relationship with Ruth, nor do the thugs who sling racial epithets at Seretse, and so the pair get married. Unfortunately, an interracial marriage upsets Ruth’s parents, Seretse’s people, and the English government. Seretse and Ruth must navigate one indignity after another once they return to Bechuanaland, and not just because seemingly everyone wants to keep them apart.

The opening scenes in England veer between cloying sweetness, and a checklist of every kind of prejudice Hibbert can imagine. There are obligatory moments where Seretse fumbles through his true feelings, for example, and another where Ruth endures being disowned by her middle-class father. Interestingly, Asante films all these scenes at night, opting for daylight only when Ruth and Seretse tie the knot. That romantic euphoria is fleeting, and the film reveals its ambition after Seretse reunites with his uncle (Vusi Kunene) in Bechuanaland. A long, pointed speech dresses down Seretse, never once letting him off the hook, while Ruth listens to proud women excoriate her for being an outsider. The challenges of interracial marriage are tough already, the film argues, but it’s another thing entirely when the marriage threatens to upend the uneasy peace of the region.

In addition to the angry Bechuanaland people, an English bureaucrat named Canning (Jack Davenport) represents the biggest challenge to Seretse and Ruth. Bechuanaland is still an English protectorate, so Canning conspires against Sereste in order to appease nearby South Africa, which is wealthy and about to institute apartheid. Canning cannily separates Sereste from Ruth, and Assante sees their pained time apart as an opportunity for growth. Through simple gestures and warm disposition, Ruth ingratiates herself among her new people. Assante gives the other white women a constant sneer, as if the country is beneath them, while Pike softens her features and comes to see Bechuanaland as her home. Ruth also has a dry sense of humor, so her way of cutting through tension helps raise her esteem among women in particular.

If Pike’s performance is reactive, defined more by gesture and silence, then Oyelowo’s performance is full of firm, soft-spoken leadership. There is a lengthy speech where Seretse defends his marriage to his people, and the mix of humility and strength is affecting. Seretse begins the film knowing he must rise to the occasion, and the challenges are denser than he anticipated. A United Kingdom includes heartbreaking twists, keeping him and Ruth apart for longer stretches, and Oyelowo/Pike effortlessly suggest that these obstacles only strengthen their resolve.

After spending decades writing for television, Guy Hibbert proves he can ably combine suspense and emotion along with political, moral, and ethical questions. His last film, Eye in the Sky, was a thrilling war procedural about an English/American drone operation in modern Kenya. Like that film, A United Kingdom is sensitive to Africa’s deep desire for self-determination, without being maudlin or condescending about it. Seretse and Ruth know in their bones that their cause is righteous, using simple appeals to decency. The English government, for all its size and power, has no courage of its convictions, only the power of the status quo. A United Kingdom weaves history and character until they’re one in the same, and the victories are all the more satisfying for it.

A United Kingdom opens Friday at Landmark’s E Street Cinema and Bethesda Row Cinema.