Earlier, I said somewhere about some book that reading it was like getting a hefty punch in the face. I was wrong. Now THIS book feels that way. Compared to it, all your "shocking" novels fade. In fact, it seems almost as if the likes of Ballard, Palahniuk, and similar hacks were all aping this book when they were writing their "nihilistic novels." 102 years after it was written, it's still unreservedly terrifying - I can only imagine the utter frenzy it must have caused upon its release!
Anyways, this is the story of a young Frenchman who engages in shady political intrigue, capping off each day with some booze and whores. Your typical debaucher, in short. Then, circumstances require him to go abroad, and he meets Clara, a beautiful-on-the-outside, hideous-on-the-inside young lady who invites him to China. He takes her up, and finds out that his debauches and misdeeds were small fry compared to the utter horrors he sees there. The sexual deviancy is just the beginning - an average day leads him to follow Clara into The Torture Garden, a place that combines beauty and death, growing all sorts of exotic, lovely flowers in the soil that's nourished with the broken bodies of the executed. Of course, the descriptions of the tortures themselves are ghastly enough, but the casual attitude that Clara takes towards death and torture is the true horror here - she admires it, she finds it beautiful, she equates it to love and passion, she actually finds sexual pleasure in it (the book's end has her in the throes of an immense orgasm).
But the book is not just another piece of deliberately shocking trash, as the "works" of the aforementioned imitators tend to be. It is redeemed by the fact that, ghastly as Mirbeau's observations are, any sane reader will be forced to admit their truth. This starts in the prologue, where a lively discussion about the role of murder in society takes place - the reader knows that murder is horrible, as do the people discussing it, but many of their observations will ring painfully true. The book frequently forces the reader to confront himself in this way.
Again, I can only imagine the reception this book had in 1899. First, Mirbeau was an atheist; second, an anarchist; third, Clara is bisexual; fourth, she has hideous fetishes; fifth, sixth, etc. Nigh every page is festering with corruption and decadence - the protagonist's, and the book's, redeeming quality is that this corruption is recognized as such. The protagonist yearns to get out of the hell-hole he's in, but he is too weak; he loves Clara's beauty, but hates the abominable sore of her soul. He hates the torture and the false beauty and the executioner who takes such pride in his awful work, but he recognizes that Europe is simply a more veiled, more "civilized" version of the same - thus China and the garden function as allegories, and the book gains a new meaning as a denunciation of all the unthinkable human brutality of modern civilization. "In this intolerable conflict you lose all joy of life and all feeling of personality, because at every moment they suppress and restrain and check the free play of your powers."
It's hard to say whether I recommend this book or not. It's quite the page-turner, certainly, but it takes rather strong nerves to finish (and then it's unlikely you'll ever re-read it). You'll have to decide for yourself. But I WOULD recommend it over the likes of Crash/Fight Club/etc. - as long as you're aiming to read a book that's violently distasteful, at least read the one that possesses some artistic merit.