Just Mercy opens with Bryan Stevenson going to visit Henry, his first death row prisoner. Bryan explains how he became passionate about criminal defense law and defending death row prisoners after an internship with the Southern Center for Human Rights in the Deep South. Stevenson discusses how he learned that the American judicial system was built to punish poor citizens more severely than the rich.
The narrative turns to the case of Walter McMillian, a black man who was wrongfully convicted of killing a white woman and subsequently sentenced to death row. In discussing Walter's case, Stevenson explains how the racial bias and presumption of guilt that led to Walter's conviction is directly linked to a history of segregation and slavery in the Deep South. Stevenson founds the nonprofit Equal Justice Initiative and takes on McMillian's case to overturn his sentence.
In between the chapters that follow both frustrations and promising developments in McMillian's case, Stevenson introduces the cases of other condemned people the EJI has represented. Stevenson advocates for children tried as adults, women raped by male prison guards, mentally ill prisoners whose disabilities are ignored by the courts, and families who are impacted by the trauma of their family member's imprisonment. Common to all of Stevenson's clients is their sensitivity. Ultimately, Stevenson advocates for the need for understanding and compassion in the project of slowing the rate of mass incarceration in the United States.
Though the EJI does not win every case, they have many successes. After six years on death row, Walter McMillian is exonerated and freed. Stevenson recounts how close he and Walter remained after the case closed. Walter's life is not necessarily happy after his release: the trauma of living on death row stays with Walter, who succumbs to dementia and physical degradation. The memoir's final scene depicts Stevenson delivering a eulogy at Walter's funeral. He explains how much he had learned from working with Walter, who taught him the importance of hope in overcoming injustice.
Stevenson ends the memoir by noting how, after rising every year since the 1980s, incarceration rates in 2014 had stabilized. The Supreme Court had also ruled in the EJI's favor, ruling that it is unconstitutional to sentence children to life sentences without parole. Stevenson concludes by saying that there is still work to be done.
