This is considered one of the classic works of gothic literature and it is easy to see why. Banned upon its original publication in 1796, it tells the story of a Monk who finds himself descending into a world of degradation. The novel itself is an attack on the brutality and hipocracy that pervaded the Catholic Church at the beginning of the 17th Century. Set in Spain, with the Inquisition as a present but distant backdrop for the majority of the novel, it shows how a Monk is brought down by his pride and quickly descends to more heinous crimes as he becomes obsessed first with a fellow monk who reveals himself as a female in disguise, and then a young innocent woman from a nearby wealthy family.
He becomes the ultimate corruptor, moving from being a figure of pious presence who inspires the awe of all those in Madrid, to a monster capable of the most heinous crimes. There are occasional supernatural elements, but these are secondary to the human story where the author exposes the horrors forced upon the people of Spain (and elsewhere) by the Church and its minions. Many of the parts of the novel are horrendous to read even now, the cold brutality of the Abbess who runs the convent towards those who transgress her laws. You can see the fictional events of the novel coloured by the anger at the similar events that occured in the Church's history.
It is a novel containing lots of the gothic themes: supernatural agencies, murder, rape, incest, poisonings, hauntings, incarcerations and a tragic love story. These are merely a means to an ends though, in a novel which attempts to expose some truths and comment on the social conditions at the time rather than merely attempting to be a shocking gothic novel. It is unsurprising that is caused such constenation amongst the establishment at the time, and despite its age it is still very much relevant today. Filled as it is with reminders of what can so easily go wrong if religious fundamentalism is given the chance to reign supreme, where choices are taken from individuals and instead given to rigid institutions.