Briefly, the story centers around Diana Bishop, an American historian who is at Oxford University studying in preparation for a presentation she is to give as a convention. Diana is a witch, but she hasn't used magic since she was seven years old and her parents, both witches, were murdered. The book begins with Diana at the Bodleian Library, where she recalls an ancient book from the stacks during her research. While she's at the library, Harkness describes the world the book is set in. There are four kinds of people in this world—humans, witches, daemons, and vampires. They all live amongst each other but don't really interact. After she reads the ancient book, however, Diana is suddenly the focus of attention for all sorts of creatures who believe there is a significant secret to their worlds hidden in the book's depths. One of those creatures is Matthew Clairmont, a vampire.
To make a long story short, Diana appears to be the only person who can recall this book, and so everyone wants a piece of her. Matthew, it appears, wants to protect her. And the two of them are quickly attracted to each other.
I can't even begin to describe how much this look reminded me of Twilight. Matthew is overly protective of Diana. Matthew withholds sex from Diana. There is a council of creatures that doesn't want vampire and witches mixing. Etc, etc, etc. It's not necessarily Harkness's fault; I think of lot of these elements are present anytime there is a male vampire involved with a female non-vampire. But at the same time, a lot of the general elements to the story felt familiar and unoriginal.
A Discovery of Witches also reminded me a bit of The Physick Book of Deliverance Dane in that the heroine was an academic from a family of witches who was looking for secrets within ancient books. As you may or may not recall, I did not like that book in large part because the heroine was such an obvious extension of the writer. The same is true here. Harkness is a scientific historian, and Diana's area of historical expertise is also science, particular alchemy. When this is the case, I feel like I get a glimpse into Ivy League academia, and I don't really like what I see. It all feels so... self-absorbed and out of touch. For instance, Diana spends day after day after day just sitting in a library reading old books. Then she goes and rows in the river. She also likes to ride horses. All rich people luxuries. It gets kind of annoying after a while.
But my biggest problem with this book was the fact that it didn't have an ending. Clearly there is going to be a sequel, but it would have been nice to know that before I started reading it. Seriously, I am pissed. At least in Twilight there was some closure at the end of the first book. Sure, the story was wrapped up, but if a person wanted to stop reading they could have. Not so here. We are left completing hanging. Grr.