During the 1980's I used to listen to a Radio Four serialisation of the book Cousin Basilio with my then girlfriend. We were taken aback by the sheer audacity of the story and the characters. It is basically the story of an empty headed wife, left alone in a sweltering Lisbon, her head full of the romances of Walter Scott and the like, falling prey to the titular Cousin who seeks to seduce her. She then falls prey to a blackmailing servant.
Although the book was written in 1878 it does not feel old fashioned. The author describes events from the point of view of the various characters, so that even unpleasant characters can at time evoke your sympathy. It also has a strong moral sense, although it scandalised readers at the time with its frank attitude to sex, and even now it is full of a languid sexuality. The book does not supply a hero or a heroine, the wife is empty headed and weak, her husband smug and complacent, their friends are idle bourgeois, rife with complacency and hypocrisy. But although there are a handful of out and out rogues, most of the characters are amusing and/or sympathetic. These are not simply caricatures, they are flesh and blood people.
The book has been blessed with an excellent translation, it really does not feel like you are reading a book written over a hundred years ago. It is certainly not a difficult read, a little wordy by modern standards, but well written and refreshing free of turgid prose.
I would compare the book to those of Thomas Mann in scope, and those of Samuel Butler and Henry Fielding for its moral indignation combined with humour.
My wife and teenage daughter both read the book in a matter of days, it really is that good. In short it is one of the best books that I have read in a long time.