The plot of "Just Mercy" follows Bryan Stevenson's relentless efforts to prove Walter McMillian's innocence. A key turning point is when Stevenson convinces the state's key witness, Ralph Myers, to recant his testimony. Myers reveals on the stand that he was coerced by law enforcement, who threatened him with the death penalty if he didn't implicate McMillian. Despite this dramatic recantation and testimony from dozens of alibi witnesses, the local judge refuses to grant McMillian a new trial, a devastating setback that highlights the depth of the systemic corruption.
Undeterred, Stevenson takes two crucial steps. First, he appears on the television news program 60 Minutes to bring national attention to the case, successfully shifting public opinion. Second, he appeals the decision to the Alabama Supreme Court. The higher court overturns the local ruling and grants McMillian a new trial. In the film's climax, Stevenson presents a motion to the new District Attorney, Tommy Chapman (Rafe Spall), to dismiss all charges. After a tense confrontation where Stevenson appeals to Chapman's conscience, Chapman joins the motion in court. The judge dismisses the case, and Walter McMillian is finally exonerated and walks free after six years on death row.
The ending titles provide crucial context: Stevenson and Eva Ansley continue their work with the Equal Justice Initiative, having saved over 140 individuals from death sentences. Walter McMillian remained friends with Stevenson but suffered from trauma-induced dementia until his death in 2013. The case of Ronda Morrison's murder was never officially solved. A final, chilling statistic reveals that for every nine people executed in the United States, one person on death row has been found to be innocent.