For a limited time, you can download Deborah Harkness' A Discovery of Witches for only 1.99$ here.
Here's the blurb:
Deep in the stacks of Oxford's Bodleian Library, young scholar Diana Bishop unwittingly calls up a bewitched alchemical manuscript in the course of her research. Descended from an old and distinguished line of witches, Diana wants nothing to do with sorcery; so after a furtive glance and a few notes, she banishes the book to the stacks. But her discovery sets a fantastical underworld stirring, and a horde of daemons, witches, and vampires soon descends upon the library. Diana has stumbled upon a coveted treasure lost for centuries-and she is the only creature who can break its spell.
Debut novelist Deborah Harkness has crafted a mesmerizing and addictive read, equal parts history and magic, romance and suspense. Diana is a bold heroine who meets her equal in vampire geneticist Matthew Clairmont, and gradually warms up to him as their alliance deepens into an intimacy that violates age-old taboos. This smart, sophisticated story harks back to the novels of Anne Rice, but it is as contemporary and sensual as the Twilight series-with an extra serving of historical realism.