The protagonist of the novel is one Cullen Post, a lawyer who left his law practice in a public defender's office, disenchanted with the need to defend guilty criminals. At one point in his life he decides to become an Episcopalian priest and continues to practice law pro bono in a small legal office called Guardian Ministries. The small group of three lawyers and an assistant in the Guardian Ministries take on cases of wrongfully-convicted persons serving time in prison. Cullen is working on the case of one Quincy Miller, an African-American accused of murdering a white lawyer. In the course of his investigation of the murder, he interviews several witnesses during the trial, some of whom eventually state that they lied. In the process, he discovers something deeper, which eventually leads him to find evidence that did not surface during Quincy's trial.
The work is well-written and has found its place in the New York Times Besteller list. Those familiar with John Grisham novels will appreciate his description of characters and events that always contain a touch of humor. Being a lawyer himself, Grisham is familiar with the legal issues involved. He himself sits on the Board of The Innocence Project in real life. Certain values are highlighted, such as concern for life, innocent or otherwise, which are truly held by Grisham himself. This concern is reflected in the characterization of the lawyers in Guardian Ministries, who sacrifice many things in order to help free the innocent in prison. The good qualities of several other persons also come to light in the course of the novel. Those who do evil are justly punished.
In The Guardians, a few violent scenes are described, but are done so in the context of the investigation being carried out. Hence, violence as such is not espoused; it is in fact presented as detestable. Vulgar language is minimal.