In the film, Dr. Martin Luther King Jr. faces immense pressure and numerous challenges as he leads the civil rights movement during 1965. The story kicks off with King receiving the Nobel Peace Prize, but his attention quickly shifts to the escalating struggle for voting rights in Selma, Alabama. The black residents of Selma, despite legal victories, still face significant barriers to registering to vote. King, along with other leaders, begins organizing nonviolent protests to draw national attention to their cause and provoke federal action. Opposition is fierce, not just from segregationists but also from some government officials who view their tactics as disruptive.

As tensions rise, peaceful marches orchestrated by King and his allies are met with brutal violence from local law enforcement and hostile citizens. These events are broadcast nationwide, eliciting widespread public outrage and increasing support for the civil rights movement. Amidst internal conflicts within the movement and external threats, King remains resolute while balancing his activism with personal struggles and a relentless campaign for justice. The narrative builds towards a pivotal demonstration designed to compel the federal government to protect African Americans' lawful right to vote.