The plot of the film is based on 1993 non-fiction book by Helen Prejean, Catholic nun known for her work with death row inmates. In the beginning of the film Prejean (played by Susan Sarandon) works in Louisiana inner-city shelter and receives letter from Matthew Poncelet (played by Sean Penn), inmate who awaits execution in Angola State Prison. Poncelet, sentenced for rape and murder of teenage couple, claims that he is innocent and wants the nun to help him set up last-ditch legal effort to prevent execution. Sister Prejean visists Poncelet in prison and slowly begins to understand his character, motivations and crimes for which he is condemned. The visits to grieving victims' relatives and obvious futility of legal efforts lead her to change her mission. She starts convincing Poncelet that admit his crimes and thus face the inevitable with some dignity and peace of mind.

Susan Sarandon and her long time companion Tim Robbins are known for their leftist (radical for US standards) views, so it isn't a problem to guess what their views are in death penalty debate. Nor does Sister Helen Prejean hide her anti-death penalty views. But DEAD MAN WALKING, at least for most of its running time, refuses to clearly take sides in the issue. Instead both sides in the debate are allowed to express their arguments and it is left to audience to make the conclusion. The movie avoids usual death penalty movie cliches - the man on the death row (fictional composite of two real-life character) is not innocent and he is not even particularly likeable. Sean Penn convincingly plays him as white-trash loser and pathetic weakling who had committed his atrocious acts because of his poor background, ignorance and emotional insecurity; this same insecurity is revealed in the way he adopts extreme racism as a way to shield himself from his own individual inability to face the inevitable. Penn's performance is much better than Susan Sarandon's; "Oscar"- awarded actress plays convincing, but too saintly character. The other roles are also superb, especially those played by Raymond J. Barry and R. Lee Ermey - both men give understated but powerful performances that show the effect of violent crime on survivors. The movie is at times slightly overlong, and in the end somewhat too manipulative - religious symbolism at the end could have been avoided, and musical score sounds too "hip" for its own good. Despite those flaws DEAD MAN WALKING should be commended for doing something which is rare in Hollywood these days - making audience think.