I wouldn't waste my time even picking up a copy of 50 Shades of Grey, which is a mass market piece of tripe for bored women.
On the other hand, the Story of O is a classic piece of erotica published in the 1950s, the authorship of which remains something of a mystery. Pauline Reage is the pen name of Dominique Aury, itself the pen name of Anne Declos, a French author and journalist. She wrote The Story of O as challenge after her lover claimed that a woman could not write and erotic novel.
There is not a lot of plot - it is a series of degrading sexual experiences involving bondage, whippings and brandings, a total subservience to the men in O's life.
However, the constrained language certainly ensures that this is genuinely erotic and not just titillating.
The past is a foreign country: they do things differently there.
The Go-Between, L P Hartley