Tim Robbins directed Dead Man Walking, but it’s really a Susan Sarandon picture. Though Robbins indulges his directorial prerogatives with a cross-cutting frenzy that ends the film on a jarringly hysterical note, Walking is far closer to the emotional resonance of Lorenzo’s Oil than to the knee-jerk burlesque of Bob Roberts. (The film was in fact originally Sarandon’s idea.) Given a more contemplative ending, it would be stunning; as it stands, it’s still one of the most compelling Hollywood dramas of recent years.

Though the book and the movie share a title, this is not a cinematic retelling of Sister Helen Prejean’s 1993 nonfiction account of her ministry to Louisiana death row inmates. Instead, it’s a dramatization, and the convicted killer is a composite. Such simplifications often yield glib results, but that’s not the case here. Robbins’ script is wonderfully specific and remarkably true to the flood of messy emotions—rage, fear, confusion—unleashed by the murder of two teenagers and the upcoming execution of Matthew Poncelet (Sean Penn) for the crime.

A liberal Catholic nun, Sarandon’s Prejean finds herself facing as many conundrums as Poncelet and the film’s other principal characters, the anguished parents of the slain youths. The nun lives in a poor African-American housing project in New Orleans, but upon answering Poncelet’s letter from death row finds herself the “spiritual adviser” to a swaggering punk who proclaims white-supremacist views to a TV interviewer. Poncelet faces death alone, and when she takes up his cause Prejean also becomes isolated: Her black friends don’t understand why she’s comforting a racist, and the victim’s parents can’t comprehend her empathy for a convicted murderer, while the prison chaplain thinks she’s overstepping her place by taking a role usually reserved for a priest.

An opponent of the death penalty, Prejean enlists attorney Hilton Barber (Robert Prosky) to save Poncelet’s life. She also wants to save his soul, however, and that involves his admission of his part in the murders. Though the film keeps Poncelet’s exact role in the crime to itself until the final moments, he’s clearly no Perry Mason guest star waiting for a last-minute confession by the real culprit; he denies killing either victim, but he admits to being present during the attack.

Since this is Prejean’s first death-row case, it’s a voyage of discovery for her as much as for the audience. She goes to visit the victims’ parents and develops a rapport with one of the fathers, Earl Delacroix (Raymond J. Barry). The other set also welcomes her, assuming that her visit means she’s no longer working with Poncelet; discovering that she still is, they uncomprehendingly throw her out of their house.

Prejean doesn’t want to take sides, and—remarkably—neither does Walking. This is a death-row tour with a human, not a political, agenda, and an anti-capital-punishment film as steely as any pro-execution text. Though the depth of the nun’s compassion is uncommon, she’s no superwoman; Sarandon’s performance conveys her bewilderment as well as it does her dedication. In Penn, the film finds an ideal foil for her; his Poncelet is profoundly dislikable, yet not a one-dimensional monster. He may not be justifiable, but he’s comprehensible.

Robbins and his crew ground these exceptional performances with credible, unshowy support. The only baroque flourishes are a few super-tight close-ups, the flashbacks both to Prejean’s childhood and to the crime—which seize control of the film in its final, more-is-less crescendo—and the Pakistani-grunge-swamp-blues score, which was composed by David Robbins, the director’s brother, and features the vocals of Nusrat Fateh Ali Khan and Eddie Vedder. (As has become customary, there’s also a Springsteen song for the final credits.) The music’s not bad, but its overweening eclecticism is a bit distracting.

Everything else about the film, however, is intensely focused. If Robbins undermines the impact of the lethal-injection climax, he’s already made the point earlier, with the deeply discomfiting scene in which Poncelet says farewell to his mother and his younger brothers. Such moments thrillingly ignore the basic Hollywood imperatives, combining inextricably the sympathetic and the distasteful, the worthy and the contemptible. Walking has the courage of such ambiguity, as well as of its boldly original quest: It’s a drama in which the heroine seeks not triumph but simply understanding.CP