A documentary about the sexual abuse suffered by young boys at the hands of Fr. Lawrence Murphy at Milwaukee's St. John's School for the Deaf since the early 50s, Alex Gibney's Mea Maxima Culpa works best when it centres on the students of St. John's but can be guilty of being too grand in scope.

Director Alex Gibney places his camera in front of three former students – Arthur Budzinksi, Terry Kohot and Gary Smith – and asks them to tell their story. The men describe Murphy as kind, charismatic and, because he was the only adult they knew who was able to sign, a father figure they needed. Arthur, Terry and Gary were only three of two hundred Murphy abused as he systematically went about isolating the kids he knew would be less inclined to speak out.

Gibney starts small, focussing on their first days in St. John's, and allows things to open and expand from there. He interviews priests - some outspoken, some who have left the priesthood when they discovered what was happening - who have astonishing things to say about the cover ups. One such 'whaaaaaat' solution was to buy an island in the Caribbean where defrocked priests would be hidden from society. Gibney uses this episode as a launch pad to investigate The Vatican's part in all this and the current Pope's inquiries into child abuse when he was a Cardinal. From there he moves on to Ballyfermot's Tony Walsh.

It's all fascinating material but it's a lot of information: Gibney is trying to squeeze a television series worth of research and revelations into a feature length documentary. The director seems to realise that the documentary is moving from the abuse of one priest into paedophilia as a whole and so tries to keep things rooted in the initial issue by cutting back to Arthur, Terry and Gary and their attempt reveal Murphy's crimes.

He might let the idea run away from him but Gibney's documentary is a fascinating one.