A bestselling novel by E. L. James, about Anastasia, a naive, young English major, who gets involved with controlling, blandly attractive Christian Grey, wealthy CEO. It does not seem well-known (or known at all) to those outside the fannish community that the book is an epic Twilight fanfiction with the serial numbers filed off. For more on this fanfic, see: GentleBlaze.

The novel's Amazon page

An Anon Reads Fifty Shades of Grey