The sexual abuse of children is often described as 'unspeakable', and perhaps this in part is why it is so difficult to combat. 'Deliver Us From Evil' takes a braver approach, choosing to transport us directly into the heart of darkness via the sickening career of the convicted Irish-born paedophile priest Oliver O'Grady. Controversially, O'Grady himself is one of the film's key interviewees. To her credit, the director Amy Berg subverts his evident wish to vindicate or downplay the reality of his crimes by counter-pointing his frequently self-serving testimony with the remarkably frank and moving interviews given to her by his victims and their parents.

Aside from these fundamentally opposite elements, 'Deliver Us From Evil' also includes legal depositions given by O'Grady and his superiors, Bishop (now Cardinal) Mahony and Monsignor Cain, prior to O'Grady's trial and conviction for sexual assault, and interviews with a number of American lawyers and theology experts. It has no narrator; instead utilising to good effect minimal textual and graphic links to supply a sense of time, place and movement.

In the primary interviews - those with O'Grady and his victims and their families - the picture of sexual abuse and victimisation painted is incredibly jarring. Berg successfully creates an astonishingly visceral sense of the evil and fear O'Grady inflicted wherever he went during his 20-year career, never losing sight of the fact that he was protected and facilitated in this by his superiors. This is to her credit as O'Grady attempts to present himself as an innocuous or innocent individual during most of his time on screen. While the scale and depravity of his abuse is known to be vast - he assaulted literally hundreds of children, including infants over a period of 20 years - Berg manages the difficult job of ensuring that 'Deliver Us From Evil' did not become a misguided plea for understanding or forgiveness. Rather than 'contextualise' O'Grady's abuse, she succeeds in creating a vivid impression of the magnitude and depth of the damage done.

A key interviewee is Bob Jyono, husband of Maria, an Irish emigrant to America, and father of Ann, who was abused by O'Grady from age five to age 12. His breaking down as he recounts the story of how they discovered that O'Grady had abused his position as a friend of the family is heartbreaking and more than any other scene delivers the sense of innocence shattered and trust betrayed that gives the film its righteous sense of moral outrage. The story of Adam, another victim, and his mother, seduced by O'Grady in order that he might gain access to her child, is similarly shocking and tragic and throughout the stories of the victims are unrelentingly emotive.

Berg deserves credit for her outstanding technical and compositional ability. Particularly effective is a scene in which, as O'Grady describes his vile abuse of a young boy, Berg shows us open-mouthed, staring statues in a church as they seem to cry out mutedly. O'Grady calmly proceeds to tell his story and here, as in many other scenes, the sense that he is simply incapable of understanding the evil of his predilection is palpable.

For Irish viewers it will undoubtedly prove strange and unsettling to see O'Grady being interviewed in and around the St Stephen's Green area, having returned to Ireland after serving several years in prison in the US. A Dublin bus trundles past at one point, and at another we see him leaning on a fence, watching children in a playground. These scenes have been digitally altered to obscure the children's faces.

Even worse is the chilling sense at one point that 'Deliver Us From Evil' may in fact be O'Grady's final attempt to somehow get at his victims. Early in the film we learn that he has extended an invitation to them to come to see him in Ireland in order for him to apologise in person (an invitation he later withdraws). Later we see him sitting in a darkened room and winking directly at the camera, saying "hope to see all of you real soon". With all that has gone before, the effect of this is heart-stopping. Is O'Grady simply incapable of normal human behavior, and thus guilty of failing to understand the seriousness of what he had done, or is this a calculated effort to intimidate or humiliate his victims? I am still not able to decide.

Aside from the interviews with O'Grady and his victims, 'Deliver Us From Evil' features a secondary' strand which attempts to link Roman Catholic theology and the institutional make-up of the church to the individual cases of abuse. It succeeds in part. One commentator in particular, the dissident theologian Father Tom Doyle, is a sympathetic and interesting figure, while an interview with a psychologist is also revealing on the subject of the church-wide problem. Besides these two, the lawyers and commentators used to build the case against the church are prone to superficial summaries of aspects of Catholicism and, although it is hard to judge, occasional over-statement.

As with all such documentaries, Michael Moore's 'Bowling For Columbine' comes to mind, there is an occasional tendency to overstep the mark in attempting to present the case for one side over the other. In seeking to build a case against the church 'Deliver Us From Evil' could be accused of being overly keen to prove that the church as an institution is responsible for O'Grady's actions, rather than O'Grady himself.

I can understand why Berg might choose to use an opening quote from the apocryphal Gospel of Thomas, presumably she wishes to make a point about the church and marginalisation, but this is misguided. A quote from a canonical text, of which there are hundreds suitable, would have been more effective.

However, as with 'Bowling For Columbine', there is a core of truth and outrage that leaves an indelibly vivid impression on the viewer. Although the subject matter is disturbing, and one could be forgiven for avoiding it on account of its potential to cause upset, this is a must see film.

Brendan Cole