“Boycotting buses in Montgomery, segregation in Birmingham, now voting in Selma. One struggle ends, just to go on to the next and the next.” The words are uttered by Martin Luther King (David Oyelowo) in a stem-winding sermon, but they offer a clue to the underlying logic of director Ava DuVernay’s remarkable film Selma. The movie does not present itself as a biography of its world-renowned protagonist, nor as a history of the movement he led. Rather, it portrays a single brief chapter in the long, ongoing struggle for civil rights, and it does so with exceptional focus and intelligence.

The movie begins with a bit of dramatic sleight-of-hand, interspersing King’s acceptance of the Nobel Peace Prize (which took place in December 1964) with a heartbreaking dramatization of the 16th Street Baptist Church bombing that had killed four girls in Birmingham the previous year. DuVernay then settles her gaze on the events leading up to three planned marches from Selma to Montgomery in 1965—marches that directly led to the passage of the Voting Rights Act later that year.

Like Lincoln, another film that had the wisdom to tell its tale in microcosm, Selma is the story not only of a man but of a process. In place of the internal horse-trading of the earlier picture, DuVernay’s movie concerns itself with the application of external leverage. Unable to persuade Lyndon Johnson (Tom Wilkinson) to push for a voting bill, King and his fellow leaders in the nonviolent movement turn to the most precious asset they have, their own bodies. The political arithmetic is as precise as it is chilling: If they demonstrate in Selma, they will be beaten, or even killed, by the forces of local Sheriff Jim Clarke and the state police; those beatings will be covered in the papers and on the news; and eventually, the activists hope, the revulsion of everyday Americans will reach a tipping point and force Johnson’s hand.

DuVernay’s film is equally stark and clear-eyed when it comes to the mechanisms used to prevent black Americans from registering to vote across the South: poll taxes, civics tests, the need to be “vouched for” by an existing voter, the publication of one’s name and address in the paper in the event that he or she successfully registers—an invitation to violence. So too, with the political stakes in question, which include not only the right to elect leaders but also to sit on juries—the same juries that, having historically been all-white, consistently acquitted any white man charged with anti-black violence.

If this makes the movie sound like a civics lesson, then I am doing it an injustice. Selma is a film of uncommon power, insight, and even humor. Oyelowo is superb in the central role of King, capturing his famous cadences without ever descending into mimicry. This is a life-sized portrait of a larger-than-life figure, and never more so than in the scenes between King and his wife Coretta (Carmen Ejogo), their marriage strained not only by the ever-present threat of violence but also by his own serial infidelities, which the movie handles with tact but does not shy away from.

The supporting cast is likewise strong, notably Colman Domingo (as Ralph Abernathy), André Holland (as Andrew Young), and Stephan James (as John Lewis), but also Lorraine Toussaint, Wendell Pierce, Jeremy Strong, Common, and Giovanni Ribisi. Cuba Gooding Jr. and Martin Sheen never quite disappear into the minor characters they play, but remarkably Oprah Winfrey (who also produced) does so with utter grace and ease.

Which brings me to Wilkinson and Tim Roth, who plays Alabama Governor George Wallace. The casting is a touch odd, and both actors take some time to settle into their roles. But crucially neither is trying to do an impression of the character he plays. They allow us to accept them gradually, without falling back on elaborate makeup or twitchy mannerisms, like the disastrous parade of presidential caricatures that populated last year’s The Butler. (Ironically, the director of the latter, Lee Daniels, was originally slated to direct Selma.)

DuVernay is working on a vastly larger scale here than she has before (her previous feature, Middle of Nowhere, was an intimate portrait of a medical student’s struggles when her husband is sentenced to prison), but she does so with extraordinary self-assurance. Whether filming the easy camaraderie of King with his friends, or the tense meetings between his Southern Christian Leadership Conference and the Student Nonviolent Coordinating Committee, or the outright horror of the “Bloody Sunday” police brutality that took place on Selma’s Edmund Pettus Bridge on March 7, 1965, she and cinematographer Bradford Young are in full control of their vision. The result is a stately, sober film, at times uplifting and at others agonizing. It’s a snapshot of a moment in time that seems both distant from our own, and yet still unbearably too close.