>> reporter: this is one victim's story in a country deeply wounded by the horrific legacy of priests abusing vast numbers of children and often getting away with it? it will be the defining issue of pope francis during his visit to once proudly catholic ireland. >> do this in memory of me. >> reporter: where many churches are now largely empty, where the institution is struggling for purpose and credibility. >> i went into the hospital when i was 12, just turned 13, i was sexually assaulted by the catholic chaplain. >> reporter: after decades of recovering, mary collins has become a powerful voice. last year she walked away from a vatican panel advising pope francis because nothing changed. she wasn't satisfied with his recent written apology. >> we wrote the pope a strong letter, a lot is good. unfortunately, he says we are