John Grisham's "The Guardians" introduces a non-profit organization called Guardian Ministries, which works to exonerate wrongfully convicted individuals, focusing on cases like that of Quincy Miller, imprisoned for murder, and Duke Russell, on death row for rape and murder. The story details the challenges faced by the organization, including financial struggles and encountering corrupt officials and dangerous individuals who benefit from the wrongful convictions. It highlights the investigative process, including gathering new evidence, re-examining old cases, and navigating the legal system, ultimately showcasing the efforts to prove innocence and secure freedom for their clients.