This extraordinary and very harrowing novel leaves a nasty, lingering residue in the reader's mind but also, amazingly, manages to strike a note of unlikely redemption.

The story of one man's quest to gain justice for victims of child abuse by Roman Catholic priests in the US, it is also much more than that. It is about how power corrupts and how the most powerful Christian church in the most powerful country on this planet systematically covered up one of the most horrific scandals of our time. It also explains how decent people, within the church and outside it, those who sought justice and truth, sometimes had to persist with almost superhuman determination and courage.

The author, Ray Mouton, writes with genuine authority; he represented the first Catholic priest charged with the abuse of children in the US. The novel is very long – almost 600 pages, and was apparently long in the writing and constantly revised. But it is not long in the reading, for it is written as a thriller, and an accomplished one at that.

Yet this format disturbed me; here is a documentary novel about many utterly horrendous crimes, written in the mode of a page-turner, a legal thriller by the likes of John Grisham or Scott Thurow or even Michael Connelly. It might seem peculiar to complain about a novel being too readable, but that is exactly what I'm doing. Because it is so fluently written, the reader drives on, not always fully aware of the full horror of what he is reading. I found that I had to return, several times, to some of the key passages to take in their true, deep and gut-wrenching import.

The factual background to the novel can be summed up, I hope accurately and fairly, thus: during the past dozen years or so, the RC Church in the US has been investigating sex abuse allegations against more than 3000 of its priests. Several completed lawsuits have resulted in multi-million dollar payouts to various claimants. Estimates of the overall settlement are that it has cost the church well over $2 billion. Several US dioceses have declared bankruptcy as a result. For example, in Texas, $31 million was paid to the many victims of just one priest.

Ray Mouton tells his complex and forensic story through the eyes of a good man, a Catholic lawyer in early middle age for whom the legal task he takes on becomes much more than a professional chore; it becomes a crusade for justice, and to some extent for redemption. This lawyer, the narrator, almost destroys himself in the process, and it is as well that Mouton manages to present him as a credible figure, for the American legal profession does not come at all well out of this narrative. Indeed the book is a devastating indictment of the cynicism and rapacity of many American lawyers and the insurance executives who collude with them, as well as the corruption and incompetence of some judges.

But the book is an even more devastating indictment of the Roman Catholic Church in the US. This is a tale of arrogance and obfuscation and denial, as wicked crimes – not just of abuse, though they are bad enough, but also of murder – are committed by members of a powerful, rich and supposedly holy organisation which then behaves in a consistently reprehensible manner as it seeks to prevent justice.

Thankfully, Mouton makes a key part of his narrative an account of the dogged efforts of two decent and immensely courageous priests who fight their own church with determination and almost unbelievable resilience. This is just and fair; it balances his assault on the Church as an institution. The Catholic lawyer who eventually helps to expose all the evil manages, despite everything he brings into the open and everything he personally endures, including the break up of his own family, to retain his own personal faith. I found this moving, even ennobling. In that sense, this book is redemptive.

The book has serious flaws, however. Towards the end some of the action switches to Rome and the Vatican City. I felt authenticity was disappearing here; some of the Rome passages read like a schmaltzy travelogue. And I wish the narrative was written in a less slick style. But some of the scenes are unforgettable; an early passage when the good lawyer confronts the priest he is representing, a serial paedophile, and hears his eerily smug and self-justifying account of his evil actions, is one of the creepiest things I've ever read. It is not written with the slightest taint of salacity.

At its core this novel is the horrendous story of innocence being defiled thousands of times. Yet you are left with the sense that despite the systematic, almost routine machinations of evil people, good must eventually prevail. But in the meantime, young life after young life has been ruined.

In God's House

Ray Mouton

Head of Zeus, £18.99